Search PubMed⌕ Search

Biomedical subjects

R Feinstein

Publications and source records attributed to R Feinstein.

53 records · Page 3Linked to original sources
PubMed1977

A new limulus assay for the detection of endotoxin.

The limulus amebocyte lysate (LAL) assay has proven to be a highly sensitive and reliable indicator of endotoxin in most biological fluids; however, it has not been a reliable indicator when used with blood because of different inhibitors present in the blood. To avoid these problems, investigators have used difficult extraction procedures, but but even with these, results were oftentimes not uniform. It was found that a recently developed inert polymer (PSI-HAP 100) has a specific affinity for endotoxin, so that is was possible to develop a simple, reliable, reproducible method for the detection of endotoxin in blood. In the assay procedure, the polymer, compressed into a 3-mm diameter bead, is incubated with 0.2 cc of heparinized whole blood. The bead is then removed from the blood, washed in pyrogen-free saline to remove any inhibitors of the LAL, and placed in a tube containing LAL. The LAL and bead are incubated together; after incubation the LAL is examined for gellation. Using this new method, it was possible to predict Gram-negative septic episodes in burn patients several days before sepsis evolved clinically.

Arthropods↗
PubMed1976

Anatomical basis for an apparent paradox concerning conduction velocities of two identified axons in Aplysia.

Larger axons usually have faster conduction velocities, lower thresholds, and larger extracellular action potentials than smaller axons. However, it has been shown that the largest fiber, R2, in the right pleurovisceral connective of the marine mollusc, Aplysia, has a higher threshold and a slower conduction velocity than does the smaller axon of cell RI, even though the amplitude of R2's spike is larger than R1's spike. One explanation of this apparent parodox is that the two axons have different "intrinsic membrane and axoplasmic constants" (Goldman, L. (1961), J. Cell Comp. Physiol. 57: 185-191). However, the deep infolding of R2's axonal membrane suggested that differences in the shape of the two axons might also account for the paradox. Accordingly, we measured the conduction velocities of the two axons and then examined the same axons in the electron microscope in order to measure their volumes and surface areas. Our morphological observations indicate that the extensive infolding of surface membrane causes R2 to have a smaller volume to surface area ratio than R1. Thus, since conduction velocity is proportional to the square root of the volume to surface area ratio (Hodgkin, A.L. (1954), J. Physiol. 125: 221-224), it is predictable that the smaller axon would have a faster conduction velocity. The results suggest that the paradoxical conduction velocities can be explained largely as resulting from differences in the shapes of the two axons. However, certain discrepancies between the measured and the predicted values suggest that other factors are contributing as well.

Animals↗
PubMed1971

Gold dermatitis.

Explore the source record for details and available documents.

Arthritis↗
PubMedDate not supplied

The effect of alcohol and barbiturate on the frequency of atrial and ventricular premature beats during sleep.

Repeated EEG and ECG monitoring during sleep was carried out in two subjects with ischemic heart disease and one presumably healthy control. All three displayed frequent ectopic heart beats. Two had ventricular and the third atrial premature beats. The study had two objectives: (1) to ascertain the distribution of ectopic beats among the stages of sleep; and (2) to ascertain the effect of alcohol and barbiturates on the frequency of premature beats. Both drugs are known to alter the pattern of sleep stages. It was found that neither atrial nor ventricular premature beats favored a particular sleep stage. Neither drug had a consistent effect on their frequency and there was no correlation with heart rate. For the most part premature beats were fewer on the second night of a procedure although a day filled with anxiety appeared to greatly increase the frequency of premature contractions.

Adult↗
PubMedDate not supplied

Violence and suicide risk assessment in the psychiatric emergency room.

Structured clinical rating scales covering 10 areas related to suicide and violence were constructed for use in a psychiatric emergency room (ER). Ninety-five ER patients were evaluated with the scales, 50 of whom were discharged after the visit and 45 of whom were admitted to the inpatient psychiatric wards of the hospital. The admitted patients were found to differ significantly from the discharged patients on every one of the 10 scales. Scores on the scales were also found to predict suicide precautions on the wards, harrassment of other patients as assessed from nursing notes, and indicators of violence on the wards. The scales were also found to have high internal reliability and high sensitivity and specificity. They appear to be helpful to clinicians in identifying patients in need of hospitalization and may also serve as limited predictors of hospital functioning.

Adult↗
PubMedDate not supplied

Association of bronchopneumonia with sinusitis due to Bordetella bronchiseptica in an experimental rabbit model.

An animal model for rhinogenic sinusitis was developed in rabbits naturally colonized with Bordetella bronchiseptica. It was found that ostial occlusion predisposes the sinus to invasion with this opportunistic bacterium and subsequent sinusitis as a result of reduced local host defense. In addition to the inflammatory lesions in the sinus, bronchitis and pneumonia were found in 84% of the experimental rabbits, suggesting that ostial dysfunction can also contribute to infectious disease of the lower respiratory tract. In such a model it is possible to study the significance of asymptomatic carriage of potential pathogens after ostial occlusion.

Animals↗
PubMedDate not supplied

Applications of random sampling to virtual screening of combinatorial libraries.

We describe statistical techniques for effective evaluation of large virtual combinatorial libraries (> 10(10) potential compounds). The methods described are used for computationally evaluating templates (prioritization of candidate libraries for synthesis and screening) and for the design of individual combinatorial libraries (e.g., for a given diversity site, reagents can be selected based on the estimated frequency with which they appear in products that pass a computational filter). These statistical methods are powerful because they provide a simple way to estimate the properties of the overall library without explicitly enumerating all of the possible products. In addition, they are fast and simple, and the amount of sampling required to achieve a desired precision is calculable. In this article, we discuss the computational methods that allow random product selection from a combinatorial library and the statistics involved in estimating errors from quantities obtained from such samples. We then describe three examples: (1) an estimate of average molecular weight for the several billion possible products in a four-component Ugi reaction, a quantity that can be calculated exactly for comparison; (2) the prioritization of four templates for combinatorial synthesis using a computational filter based on four-point pharmacophores; and (3) selection of reagents for the four-component Ugi reaction based on their frequency of occurrence in products that pass a pharmacophore filter.

Combinatorial Chemistry Techniques↗
PubMedDate not supplied

Persistence of polyomavirus in adult SCID C.B-17 mice.

C.B-17 mice with the Severe Combined Immune Deficiency (SCID) mutation were infected with the naturally occurring murine polyomavirus. Using the Polymerase Chain Reaction (PCR) technique, persistence of polyomavirus was followed in different tissues of the mice between 24 hours and 2 months post infection (p.i.). Viral DNA appeared by 3-5 days and was detected in all studied organs by 3 weeks p.i. From 4 weeks to 2 months p.i. viral DNA was present at high levels in all studied organs in all of the animals. As controls normal C.B-17 and A/Sn mice were used. Viral DNA appeared by 2-4 days. The infection reached a peak around 1 week p.i. This was followed by a clearing stage and viral DNA was no longer detectable by 4-5 weeks p.i. Most organs studied with PCR were also examined histologically, but no lesions were observed. Consequently persistence and organ distribution of polyomavirus in adult SCID mice differs greatly from that in normal adult mice.

Animals↗