What to Know Before Buying Pipettes

  • BS Media
  • | 07 Oct 2016
Why is it important to know the viscosity of the samples that will be aspirated / dispensed?
 
The viscosity of the sample will have a direct influence on which pipette is required. For aqueous samples which are low viscosity, an air displacement pipette is ideal. These pipettes are driven by a piston in an airtight sleeve which generates a vacuum. For more viscous or heavy liquids, a positive displacement pipette should be used. These pipettes are driven by a disposable piston which comes into direct contact with the sample.

How will samples required for PCR, ELISA, or other immunoassay applications affect which pipette should be used?
 
PCR, ELISA, and many other immunoassay methods utilize microwell plates. Microplates come in many configurations: 6, 24, 96, 384, and 1536 well plates arranged in a 2x3 matrix are typically used. In order to accommodate faster throughput with such methods, many pipette manufacturers offer multichannel pipettes. These allow for faster pipetting of multiple samples: instead of having to fill 96 wells individually, an 8 channel pipette can be used, reducing the number of aspirations and dispenses to 12.
 
How does the volume of samples being worked with influence which pipette is the best fit?
 
Pipettes come in a variety of different sizes to suit whichever volume needs are required. If you know you will always be pipetting the same volume of liquid, then a fixed volume pipette will be best. If the amount to be pipetted is changing from sample to sample, then a variable pipette will be ideal.
 
Counterfeit and substandard medications are a serious problem in the developing world, potentially harming patients who desperately need medical treatment.

Some of these drugs, including the antibiotics ciprofloxacin and ceftriaxone, have been deemed essential by the World Health Organization for the treatment of infections. However, chemists in developing countries often do not have expensive instruments to determine whether a pill is genuine.

Now, a simple paper-based test may be the answer.

Instead of a $30,000 machine, a $1 paper card can test a drug in three minutes to determine whether the medication is inactive or of substandard quality. The tests come in 20-card packets.

Read more: Paper-based Test Identifies Bogus and Poor Quality Drugs
In what could be a major step forward in our understanding of how cancer moves around the body, researchers have observed the spread of cancer cells from the initial tumour to the bloodstream.

The findings suggest that secondary growths called metastases 'punch' their way through the walls of small blood vessels by targeting a molecule known as Death Receptor 6 (no, really, that's what it's called). This then sets off a self-destruct process in the blood vessels, allowing the cancer to spread.

According to the team from Goethe University Frankfurt and the Max Planck Institute in Germany, disabling Death Receptor 6 (DR6) may effectively block the spread of cancerous cells - so long as there aren't alternative ways for the cancer to access the bloodstream.
 
"This mechanism could be a promising starting point for treatments to prevent the formation of metastases," said lead researcher Stefan Offermanns.
 
Catching these secondary growths is incredibly important, because most cancer deaths are caused not by the original tumour, but by the cancer spreading.
 
To break through the walls of blood vessels, cancer cells target the body's endothelial cells, which line the interior surface of blood and lymphatic vessels. They do this via a process known as necroptosis - or 'programmed cell death' - which is prompted by cellular damage.
 
According to the researchers, this programmed death is triggered by the DR6 receptor molecule. Once the molecule is targeted, cancer cells can either travel through the gap in the vascular wall, or take advantage of weakening cells in the surrounding area.
Friday, 30 September 2016 21:07

Blood Test for Colorectal Cancer - Epigenomics AG

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Despite recommendations, many people in the target age group are not getting screened for colorectal cancer. However, a new blood-based screening test may help boost those rates because of its simplicity and convenience for the patient. The downside is that the new test is not as sensitive or accurate as a colonoscopy or the other recommended screening approaches.

Approved in April 2016, the Epi proColon (Epigenomics AG) is the first blood-based colorectal screening test to get a thumbs-up from the US Food and Drug Administration (FDA).

This molecular test detects methylated Septin 9 DNA in plasma, which is increased in colorectal cancer and can be found in tumor DNA that has been shed into the bloodstream from both colon and rectal sites. This makes it a differential biomarker for the early detection of colorectal cancer, according to the manufacturer.

Available in Europe since 2012, it is also being marketed in other countries, including China.

Read more: Blood Test for Colorectal Cancer: The Last Resort?
Wednesday, 28 September 2016 14:43

New finding: Biobank storage time affects blood test results

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The amount of time a blood sample has been stored at a biobank may affect the test results as much as the blood sample provider’s age. These are the findings of a new study from Uppsala University, which was published in the scientific journal EBioMedicine. Until now, medical research has taken into account age, sex and health factors of the person providing the sample, but it turns out that storage time is just as important.

They analysed 380 different samples from 106 women between the ages of 29 and 73. To study the impact of storage time, only samples from 50-year-old women were used in order to isolate the time effect. 108 different proteins were analysed. In addition to how long a sample had been frozen, the researchers also looked at what year the sample was taken and the age of the patient when the sample was taken.

‘We suspected that we’d find an influence from storage time, but we thought it would be much less’, says Professor Ulf Gyllensten. ‘It has now been demonstrated that storage time can be a factor at least as important as the age of the individual at sampling.’

Blood from biobanks has been used in research aimed at producing new drugs and testing new treatment methods. The results of this study are important for future drug research, but it is not possible or necessary, to repeat all previous biobank analyses.


Read more: New finding: Biobank storage time affects blood test results
Wednesday, 28 September 2016 14:33

Sabotaging flagella of bacteria to halt infections

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Some bacteria have the ability to ‘swim’ in a controlled fashion through the use of appendages called flagella. Researchers think that disabling these flagella is a key step towards infection control.

Motile bacteria move through the function of flagella. These appendages rotate, which propels an organism forwards. This is a little like the propellers on a boat. Some bacteria have one flagellum, others have many, and some possess none at all. Some of the bacteria regarded as human pathogens have flagella. An example of a flagellate bacterium is the ulcer-causing Helicobacter pylori, which uses multiple flagella to propel itself through the mucus lining to reach the stomach epithelium. Some flagella also serve a function in environmental detection, sensing different conditions and signalling to a bacterium to move to or away from a given niche.

Read more: Sabotaging bacteria to halt infections
Tuesday, 27 September 2016 13:49

Neutrophil disorders and their management

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Neutrophil disorders are an uncommon yet important cause of morbidity and mortality in infants and children. This article is an overview of these conditions, with emphasis on clinical recognition, rational investigation, and treatment.

Neutrophil disorders
  • Disorders of neutrophil number (neutropenia)
  • Disorders of neutrophil function
Neutrophil disorders are an uncommon, yet important, cause of morbidity and mortality in infants and children and should be considered when investigating children for immunodeficiency. They are especially likely when the clinical presentation includes features such as oral ulcers and gingivitis, delayed separation of the umbilical cord, uncommon infections such as hepatic or brain abscesses, uncommon organisms such as S marcescens or Pseudomonas spp, or when the individual has features of syndromic conditions associated with neutropenia or neutrophil dysfunction. All patients with recurrent oral infections, skin abscesses, perianal and perirectal abscesses, poor wound healing, sinopulmonary infections, or deep visceral abscesses should be evaluated for defects in phagocyte function. Appropriate investigations can lead to specific diagnoses, and general and specific management measures can reduce both mortality and morbidity and permit genetic counselling and antenatal diagnosis in some cases.

Read more: Neutrophil disorders and their management
Tuesday, 27 September 2016 12:32

Interpreting Plates - Colony Morphology

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Bacteria grow tremendously fast when supplied with an abundance of nutrients. Different types of bacteria will produce different-looking colonies, some colonies may be colored, some colonies are circular in shape, and others are irregular. The characteristics of a colony (shape, size, pigmentation, etc.) are termed the colony morphology. Colony morphology is a way scientists can identify bacteria. In fact there is a book called Bergey's Manual of Determinative Bacteriology (commonly termed Bergey's Manual) that describes the majority of bacterial species identified by scientists so far.

Although bacterial and fungi colonies have many characteristics and some can be rare, there are a few basic elements that you can identify for all colonies:
  • Form - What is the basic shape of the colony? For example, circular, filamentous, etc.
  • Elevation - What is the cross sectional shape of the colony? Turn the Petri dish on end.
  • Margin - What is the magnified shape of the edge of the colony?
  • Surface - How does the surface of the colony appear? For example, smooth, glistening, rough, dull (opposite of glistening), rugose (wrinkled), etc.
  • Opacity - For example, transparent (clear), opaque, translucent (almost clear, but distorted vision, like looking through frosted glass), iridescent (changing colors in reflected light), etc.
  • Chromogenesis (pigmentation) - For example, white, buff, red, purple, etc.
 
Cholera sickens 3 million to 5 million people around the world every year, leading to 100,000 to 120,000 deaths, many of them in the Indian subcontinent, where cholera has been endemic for centuries.
 
People with blood type O often get more severely ill from cholera than people of other blood types. In people with blood type O, scientists found that cholera toxin hyperactivates a key signaling molecule in intestinal cells. High levels of that signaling molecule lead to excretion of electrolytes and water – in other words, diarrhea. Cholera is marked by severe diarrhea that can lead to dehydration, shock and even death.

The researchers confirmed their results in an intestinal cell line originally derived from a person with blood type A. The cell line was modified to produce the type O antigen instead. They found that cholera toxin induced roughly double the amount of the key signaling molecule in cells with type O antigen than in those with type A.
 
Fleckenstein isn’t sure why cholera toxin induces different responses in cells with different blood group antigens on their surfaces.
 
“The cholera toxin is known to bind weakly to the ABO antigens, so they may be acting as decoys to draw the toxin away from its true target,” Fleckenstein said. “It may be that the type O antigen just isn’t as good of a decoy as the type A antigen.”
Tuesday, 27 September 2016 11:47

Automated Gram Stainer

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These days, your microbiology lab faces increased staffing, time and workflow pressures. Yet you can’t let that influence your quality standards: accuracy, time-to-results and full traceability for accreditation. Automated and designed for intuitive workflow, PREVI® Color Gram gives you confidence in the results you provide. It makes Gram staining easy and safe while ensuring accurate, standardized results in minutes.
 
The Centers for Disease Control and Prevention (CDC) today released the first solid evidence that a man infected with Zika, but who never develops symptoms, can sexually transmit the virus to a female partner.

An article published online in the agency's Morbidity and Mortality Weekly Report (MMWR) described the case of a woman who contracted Zika after having condomless vaginal intercourse and fellatio with a male partner after he came back from the Dominican Republic, where mosquitos are spreading the virus. The man said he had been exposed to mosquitos during his travels, but had not experienced fever, rash, conjunctivitis, or other hallmarks of Zika before or after returning to the United States. He said he had felt fatigued, but chalked that up to travel.

The man subsequently tested positive for antibodies against both Zika virus and dengue virus. The woman, who developed fever, rash, and other Zika symptoms, tested positive for Zika virus RNA in her urine.
The authors of the MMWR article, except for one CDC investigator, were public health officials in Maryland, where the case came to light.
It is already known that the Zika virus can be sexually transmitted by infected men who are symptomatic. However, most people who are infected with Zika do not experience symptoms.
 
Development of a novel collagen wound model to simulate the activity and distribution of antimicrobials in soft tissue during diabetic foot infection.

Additional Info

  • File Name Development of a novel collagen wound model to simulate the activity and distribution of antimicrobials in soft tissue during diabetic foot infection.
  • Year 2016
  • Author(s) Bianca L Price
  • Publisher American Society for Microbiology (ASM) http://aac.asm.org
  • Size 6.745 MB
  • File Format .pdf
  • Download http://aac.asm.org/content/early/2016/09/07/AAC.01064-16.full.pdf+html
Description: Uniquely organized by symptom rather than organ or pathology, Roger Sanders’s Clinical Sonography, 4e, not only ensures mastery of the content and competencies required for diagnostic sonography, it teaches students to think critically and “sonographically” as they prepare for certification exams and clinical practice. In every chapter, students first encounter a diagnostic problem to be solved and then follow pathways of exploration that help them identify the cause of the original presenting symptom.

Retaining its trademark concise, easy-to-understand writing style, consistent format, and clinical approach, the Fifth Edition is enhanced by a revised organization, new images and in-book learning tools, new content that reflects today’s practice environment, and a revised art and design program designed to meet the needs of today’s highly visual students.

Additional Info

  • File Name Clinical Sonography: A Practical Guide, 4th Ed.
  • Edition 4th
  • Year 2007
  • Author(s) Tom C. Winter Roger C. Sanders
  • ASIN B008UZ1DPS
  • Publisher Lippincott Williams & Wilkins; 22477th edition (October 1, 2007)
  • Size 33.1 MB
  • File Format .pdf
Description: Uniquely organized by symptom rather than organ or pathology, Roger Sanders’s Clinical Sonography, 4e, not only ensures mastery of the content and competencies required for diagnostic sonography, it teaches students to think critically and “sonographically” as they prepare for certification exams and clinical practice. In every chapter, students first encounter a diagnostic problem to be solved and then follow pathways of exploration that help them identify the cause of the original presenting symptom.

Retaining its trademark concise, easy-to-understand writing style, consistent format, and clinical approach, the Fifth Edition is enhanced by a revised organization, new images and in-book learning tools, new content that reflects today’s practice environment, and a revised art and design program designed to meet the needs of today’s highly visual students.

Additional Info

  • File Name Clinical Sonography: A Practical Guide, 4th Ed.
  • Edition 4th
  • Year 2007
  • Author(s) Tom C. Winter Roger C. Sanders
  • ASIN B008UZ1DPS
  • Publisher Lippincott Williams & Wilkins; 22477th edition (October 1, 2007)
  • Size 33.1 MB
  • File Format .djvu
Description: BRS Biochemistry, Molecular Biology, and Genetics is an excellent aid for USMLE Step 1 preparation and for coursework in biochemistry, molecular biology, and genetics. Fully updated for its sixth edition, chapters are written in an outline format and include pedagogical features such as bolded key words, figures, tables, algorithms, and highlighted clinical correlates. USMLE-style questions and answers follow each chapter and a comprehensive exam appears at the end of the book.

Additional Info

  • File Name BRS Biochemistry, Molecular Biology, and Genetics 6th Ed.
  • Edition 6th
  • Year 2013
  • Author(s) Michael Lieberman PhD, Rick Ricer MD
  • ISBN-10 1451175361
  • ISBN-13 978-1451175363
  • Publisher LWW; Sixth edition (September 14, 2013)
  • Size 49 MB
  • File Format .pdf
  • Password bioscience.pk
Description: Long recognized as the standard general reference in the field, this completely revised edition of  Grainger and Allison?s Diagnostic Radiology provides all the information that a trainee needs to master to successfully take their professional certification examinations as well as providing the practicing radiologist with a refresher on topics that may have been forgotten. Organized along an organ and systems basis, this resource covers all diagnostic imaging modalities in an integrated, correlative fashion and focuses on those topics that really matter to a trainee radiologist in the initial years of training.
 
"...the latest edition ...  continues the fine tradition set by its predecessors.... help young radiologists to prepare for their examinations and continue to be a source of information to be dipped in and out of ... senior radiologists will also find the book useful ..." Reviewed by: RAD Magazine March 2015
 
 "I am sure the current edition will be successful and help young radiologists to prepare for their examinations and continue to be a source of information to be dipped in and out of..." Reviewed by RAD Magazine, March 2015

Additional Info

  • File Name Grainger & Allison's Diagnostic Radiology: 2-Volume Set, 6th Ed.
  • Volume 2-Volume Set
  • Edition 6th
  • Year 2014
  • Author(s) Andy Adam CBE MB BS (Hons) PhD FRCP FRCR FRCS FFR RCSI (Hon) FRANZCR (Hon) FACR (Hon) FMedSci (Author), Adrian K. Dixon MD MD(Hon caus) FRCP FRCR FRCS FFRRCSI(Hon) FRANZCR(Hon) FACR(Hon) FMedSci (Author), Jonathan H Gillard BSc MA MD FRCR FRCP MBA (Author), Cornelia Schaefer-Prokop MD PhD (Author), Ronald G. Grainger MB ChB(Hons) MD FRCP DMRD FRCR FACR(Hon) FRACR(Hon) (Author), David J. Allison BSc MD MRCS LRCP MB BS DMRD FRCR FRCP (Author)
  • ISBN-10 0702042951
  • ISBN-13 978-0702042959
  • Publisher Churchill Livingstone; 6 edition (July 3, 2014)
  • Size 308 MB
  • File Format .pdf
  • Password bioscience.pk

Since some species exhibit periodicity (i.e. circulation of microfilariae in increased numbers at certain times of the day), blood should be collected at the correct time to improve the chances of detection. For Wuchereria bancrofti and Brugia malayi showing nocturnal periodicity, blood should be collected at night between 10 p.m. to 4 a.m. Microfilariae are present in greater numbers in capillary blood than in venous blood; therefore, skin puncture is preferred. Usually microfilariae are scanty in peripheral blood so that concentration techniques may be necessary for their demonstration.

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