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Biomedical subjects

B R Jennings

Publications and source records attributed to B R Jennings.

At least 19 recordsLinked to original sources
PubMed1999

A novel high molecular weight fibrinogenase from the venom of Bitis arietans.

A fibrinogenase (Ba100) with an apparent molecular mass of 100 kDa under non-reducing conditions and a pI of 5.4 was purified from the venom of the African puff adder (Bitis arietans) by fibrinogen affinity chromatography. Under reducing conditions the protease dissociates into subunits of 21 kDa and 16 kDa. N-Terminal amino acid sequencing showed these two chains to have 66.7% homology and homology to C-type lectins. The fibrinogenase activity of Ba100 cleaves the Aalpha and Bbeta chain of fibrinogen rendering the molecule unable to polymerise into fibrin clots. Ba100 inhibited platelet aggregation in platelet rich plasma, and clot formation in whole blood, in a concentration dependent manner.

Amino Acid Sequence↗
PubMed1989

Beta 2-microglobulin levels in patients with renal insufficiency.

beta 2-microglobulin (beta 2M) has been implicated in the pathogenesis of amyloidosis in long-term dialysis patients. beta 2M levels were measured in patients with chronic renal failure: before and after conventional hemodialysis in 30, before and after high-flux (HF) hemodialysis in 35, and during the first hemodialysis treatment in five patients, as well as in the serum and peritoneal fluid of 13 patients who were receiving continuous ambulatory peritoneal dialysis (CAPD) and in the serum and urine of three patients who had received kidney transplants. Dialysis patients had markedly elevated beta 2M levels; prehemodialysis values were not significantly different for patients receiving conventional v HF hemodialysis. Most of these patients were functionally anephric, and the beta 2M levels did not correlate with age, sex, or time on dialysis. In patients receiving conventional hemodialysis using cellulose acetate membrane, beta 2M levels increased 25.4% after hemodialysis, whereas in patients receiving HF hemodialysis using polysulfone membrane, beta 2M levels decreased significantly (43.0%) after hemodialysis. End-stage renal disease patients dialyzed for the first time had beta 2M values significantly lower than the other two groups because of residual glomerular filtration rate (GFR). CAPD patients also had lower values because they had an estimated loss of 80.4 mg/d of beta 2M in the dialysate fluid. In patients with chronic renal failure, beta 2M levels paralleled the increase in serum creatinine. Patients who received kidney transplants had a dramatic decrease in beta 2M levels that correlated with improvement in GFR. beta 2M correlated with the residual GFR, and its removal was membrane-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Absence of myelin basic protein in granular cell tumors.

Thirty-one granular cell tumors were studied for the presence of myelin basic protein (MBP) using a monoclonal antibody with a characterized specificity and an immunoperoxidase technique. The tumors studied were from all areas of the body, from both sexes, and from nine decades of age. All the tumors stained negatively for MBP. One brief report using a monoclonal antibody had noted positive staining for MBP in granular cell tumors. A more recent study using polyclonal antibodies found negative staining for MBP in Schwann cell neoplasms including granular cell tumors. This study, using an immunohistochemical technique, demonstrated the absence of an MBP marker in granular cell tumors of diverse location despite the fact that granular cell tumors are widely held to be of Schwann cell origin.

Antibodies, Monoclonal↗
PubMed1987

Serology of Naegleria fowleri and Naegleria lovaniensis in a hospital survey.

An avidin-biotin horseradish peroxidase method was used to detect antibodies to Naegleria fowleri and N. lovaniensis in human serum samples. Antibodies were detected in 101 specimens from 115 hospital patients ranging in age from 15 to 98 years. Class-specific anti-immunoglobulins identified antibodies as IgG and IgM. IgG antibody titers to both species ranged from 1:20 to 1:640. Seven of 15 serum samples collected from newborn infants also demonstrated IgG antibodies to these organisms with a titer range of 1:20 to 1:80. The immunoperoxidase test and Western blot analysis of selected serum samples demonstrated a close similarity in serological results between N. fowleri and N. lovaniensis.

Adolescent↗
PubMed1986

Electrofluorescence study of polycyclic hydrocarbon diol-epoxide binding to DNA.

By the use of a novel electrofluorescence method, estimates have been made of the geometry of binding to DNA of racemic mixtures of the anti-diol-epoxide derivatives of three polycyclic hydrocarbon carcinogens. These anti-configurations bind in a manner consistent with the planar diol-epoxide ring's being inclined at approximately 50 degrees to the DNA axis. This is true for the derivatives of benzo(a)pyrene, benz(a)anthracene and 3-methylcholanthrene. This binding is thus different from the regular intercalative interaction associated with the native hydrocarbons. As the (+ anti)-diol-epoxides are thought to be the initiatory compounds for carcinogenesis, the common binding characteristics for the three hydrocarbons may be significant in understanding the molecular interactions precursive to cancer.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1986

Selective screening of hospitalized patients for the presence of asymptomatic hepatitis B virus carriage: predictability based on census tract data.

Review of all hepatitis B surface antigen-positive patients reported to the county health department over the past 3 years showed that 60% of patients had been diagnosed at our hospital, which serves an inner city, predominantly black, indigent population. Sera from 524 adult patients admitted to the hospital were prospectively collected and tested for hepatitis B surface antigen, eight (1.5%) of which were antigen-positive. Census tract data allowed us to perform selective screening of sera from 95 other patients who were subsequently hospitalized and deemed "high risk" for hepatitis B infection. Nine of 95 (9.5%) selectively screened samples were positive for hepatitis B surface antigen, which represented a significantly higher rate of antigen carriage (P less than 0.0001) in hospitalized patients from "high risk" areas than that found in the general population screen. The methodology presented herein may be useful in providing a means of identifying hepatitis B surface antigen-positive patients from adult, urban, indigent care populations.

Adult↗
PubMed1985

Effect of additives on liposomes: an electric birefringence study.

Under the influence of an electric field, vesicles in suspension partially deform or orientate, rendering the medium optically birefringent. The amplitudes of the birefringence under fields of variable amplitude lead to evaluation of the anisotropy of the electrical delta alpha and optical delta G polarisabilities of the vesicles. By using pulsed fields, rates of establishment and decay of birefringence enable vesicle sizes d to be measured. Samples of 9:1 phosphatidylcholine-phosphatidylserine liposome suspension in water were studied in the presence of various additives, including sucrose, an antibiotic (streptomycin), a steroid (dexamethasone), an anaesthetic (lignocaine) and a fluidising agent (benzyl alcohol). The changes in the three parameters delta alpha, delta G and d were different for each additive and are thought to be indicative of the mode of interaction of each. Electric birefringence also appears to be a rapid means of detecting structure changes.

Benzyl Alcohol↗
PubMed1984

Electric birefringence as a means of studying the effect of anaesthetics on liposomes.

Birefringence can be induced in liposome suspensions using electric fields. The fields interact predominantly with anisotropic electrical polarisabilities which give rise to induced dipole moments. Using pulsed electric fields, the optical and electrical polarisabilities and the geometrical size of the liposomes can be measured simultaneously. These parameters have been found to be very sensitive to the presence of small amounts of fluidising additives of polar and ionic nature. Illustrative data are presented for the influence of the amines ammonium chloride, methyl ammonium chloride and lignocaine and of benzyl alcohol on phosphatidylcholine/serine liposomes. Structural changes in the vesicle membranes were detected, which appeared to correlate with the biological functions, thus indicating that electric birefringence is a rapid and useful method for studying interactive phenomena in lipid membrane systems.

Anesthetics↗
PubMed1983

Study of hyaluronic acid flexibility by electric birefringence.

Transient-electric-birefringence experiments were conducted on four samples of hyaluronic acid over the molecular-mass (M) range 5 X 10(4)-4 X 10(6) in dilute aqueous solution. The geometrical, optical and electrical characteristics were monitored via the rotary relaxation times, optical-polarizability antisotropies and electrical polarizabilities respectively. Each indicates the molecular conformation to be consistent with some degree of rigidity at low M but that this does not persist at high M. The molecules do not become true random coils, but are best characterized in terms of a persistence length of 20 nm or 20 disaccharide units.

Animals↗
PubMed1983

Interaction of chromosomal stains with DNA. An electrofluorescence study.

A novel fluorescence procedure has been used to study the binding characteristics of DNA with three modern fluorochromes currently used in chromosome cytochemistry. The transient changes in the polarised components of fluorescence have been recorded for dye-tagged DNA solutions when subjected to short duration electric pulses. From these data, it has been inferred that, like ethidium bromide, berberine sulphate and quinacrine mustard both intercalate the DNA structure whilst the bi-benzimidazole derivative Hoechst 33258 binds with a distinctively different geometry, probably within the helical grooves.

Animals↗
PubMed1983

Electro-optical fluorescence studies on the DNA binding of medically active drugs.

By measuring the transient changes in each of the polarized components of fluorescence during the application of a pulsed electric field to a solution of macromolecules, a method has been developed for evaluating the binding characteristics of fluorescent chemotherapeutic agents to DNA. It is shown that whereas quinacrine and berberine intercalate the DNA helix, hydroxystilbamidine does not. Furthermore, measurements on both the native and the diol-epoxide forms of benzo(a)pyrene show that the former is consistent with an intercalation type of binding, whilst the latter appears to be more inclined to the major DNA axis and may possibly be associated with the external helical grooves. The significance of these findings is discussed.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1983

Comparison of two commercially available isolation systems for Chlamydia trachomatis.

In a comparison of two commercially available chlamydial isolation systems in which cycloheximide-treated McCoy cell monolayers are used, the system from Bartels Immunodiagnostic Supplies, Inc., Bellevue, Wash., was found to be superior to that from M. A. Bioproducts, Walkersville, Md. for the detection of Chlamydia trachomatis by iodine staining. Of 288 clinical specimens run in parallel, 47 (16.3%) were positive, with 16 of 47 positive results detected in the Bartels system only and 1 of 47 positive results detected in the M. A. Bioproducts system only (P less than 0.001). A comparison of the number of inclusion-forming units per cover slip from clinical specimens and passaged isolates also showed that the Bartels cell system demonstrated higher inclusion counts than the M. A. Bioproducts system. In routine clinical use, overall isolation rates were higher (P less than 0.001) and contamination rates were lower (P less than 0.001) with the Bartels system as compared with results obtained in a previous time period in which the M. A. Bioproducts system was used.

Chlamydia Infections↗
PubMed1982

Beta-lactamase testing of staphylococci in a commercial broth microdilution minimum inhibitory concentration system.

Beta-Lactamase testing of clinical isolates of staphylococci may be performed in commercial broth microdilution minimum inhibitory concentration plates, using a chromogenic cephalosporin reagent directly in a well containing a noninhibitory concentration of a semisynthetic penicillin which serves as an inducer. A total of 115 staphylococcal isolates tested in 0.25 to 0.50 microgram of methicillin per ml in Mueller-Hinton broth showed 100% correlation with beta-lactamase tests performed on Mueller-Hinton agar, using 1-microgram oxacillin disk as an inducer.

Cephalosporins↗