Biomedical subjects

J B Robinson

Publications and source records attributed to J B Robinson.

At least 19 recordsLinked to original sources

PubMed1995

Effect of skin-graft harvesting on hair growth; implications for the study of alopecia.

An experiment using guinea pigs was performed to demonstrate the feasibility of repeated skin-graft harvesting as a model system in the study of diffuse alopecia. In response to four split-thickness skin harvests from the same site at 2-week intervals, the number of hairs observed and follicular area doubled, implying a transition of hair follicles from vellus to terminal, compared with ungrafted control skin from the alternate side of the same animals. The guinea pig may serve as a future model for the study of diffuse alopecia because its hair growth patterns are similar to those observed in humans.

Alopecia↗

PubMed1995

Irreversible inhibition of rat liver mitochondrial MAO A and MAO B by enantiomers of deprenyl and alpha-methylpargyline.

Using rat liver mitochondrial monoamine oxidase (MAO) A and MAO B, the possible influence of stereochemical factors upon the irreversible inhibition by propargylamine derivatives has been studied using the enantiomers of deprenyl and of alpha-methylpargyline. Whether studying the inhibition of MAO A or MAO B, little difference was found among enantiomeric pairs in the first-order rate constant (k2) for formation of the enzyme inhibitor adduct. Similarly, and with the exception of (S)-D-(+)-deprenyl (k2 = 0 or an extremely low value at MAO A), the computed value of k2 for the individual enantiomers showed little variation between MAO A and MAO B. These results suggest that inhibitor selectivity towards a particular form of the enzyme is determined predominantly at the competitive phase of the inhibition.

Animals↗

PubMed1995

Iloprost enhances survival of axial-pattern skin flaps in an ischemia-reperfusion model.

Iloprost, a stable prostacyclin analogue, significantly enhances the survival of an axial-pattern groin flap in rats after ischemia-reperfusion. Treated flaps showed viability over 90 percent of their area 7 days after an 8-hour ischemic episode, whereas the saline-treated controls were viable over only 20 percent of their area (p = 0.002). This effect was seen at a low (10 ng/kg) dosage, and no apparent side effects were noted.

Animals↗

PubMed1995

Frontal sinus obliteration: a comparison of fat, muscle, bone, and spontaneous osteoneogenesis in the cat model.

The obliteration of the frontal sinus is frequently necessary in the appropriate treatment of trauma, chronic infection, and benign tumors, but the various methods have not been directly compared previously. This study compares four treatment groups (seven cats per group) specifically of implantation of autologous fat, muscle, and bone and spontaneous osteogenesis done using a strictly standardized operative technique in an unfractured, uninfected feline frontal sinus model. All methods studied were effective in sinus obliteration; however, significant morbidities occurred at the donor sites when autologous tissue transplantation was used. Therefore, spontaneous osteogenesis appears to be the method of choice for frontal sinus obliteration.

Adipose Tissue↗

PubMed1994

Effectiveness of a new non-thrombogenic bio-adhesive in microvascular anastomoses.

Negatively-charged fibrin glue was successfully prepared by combining human cryoprecipitate with succinic anhydride. The resulting bio-adhesive was tested for thrombogenicity and tensile strength by applying it to three groups of Sprague-Dawley rat femoral-artery anastomoses (6 suture, 2 suture, and no suture anastomoses). Anastomoses were tested by a standard patency test over 7 days. Both the 6-suture and 2-suture anastomoses with negatively-charged fibrin glue had 100 percent patency rates and no pseudoaneurysm formation over 7 days. When positively-charged fibrin glue was applied to sutured anastomoses, patency rates decreased gradually to 50 percent over 7 days. Fibrin glue alone (whether negatively- or positively-charged) does not have the tensile strength to maintain an anastomosis without sutures. However when applied to a two-suture anastomosis, the breaking strength of the anastomosis is more enhanced by the negatively-charged fibrin glue.

Anastomosis, Surgical↗

PubMed1992

Role of divalent cations in the subunit associations of complex flagella from Rhizobium meliloti.

Rhizobium meliloti, a symbiotic, nitrogen-fixing soil bacterium with complex flagella, as well as other members of the family Rhizobiaceae, rapidly lost motility when suspended in buffers lacking divalent cations but retained good motility in buffers containing calcium, magnesium, barium, or strontium. Loss of motility was associated with loss of flagella from the cells. Analysis of flagella by sedimentation, gel electrophoresis, and electron microscopy revealed that removal of divalent cations from the complex flagella of R. meliloti resulted in extensive dissociation of the flagellar filaments into low-molecular-weight subunits. Accordingly, divalent cations such as calcium and magnesium that are normally present at high concentrations in the soil solution may be crucial to the assembly and rigidity of complex flagella.

Calcium↗

PubMed1991

"Jumping" translocations involving band 3q13.3 in a case of acute monocytic leukemia.

We report a case of acute monocytic leukemia (FAB-5a) with a very aggressive clinical course and multiple chromosomal abnormalities. There were several sublines, each with trisomy 8 and a translocation involving 3q13.3 as a common breakpoint region. This region is an uncommon site of chromosomal breakage in malignancies and has not hitherto been reported as a breakpoint site in "jumping" translocations.

Aged↗

PubMed1991

Synthesis, biological evaluation and quantitative structure activity relationship analysis of nuclear-substituted pargylines as competitive inhibitors of MAO-A and MAO-B.

A series of nuclear substituted derivatives of pargyline has been prepared and tested (under controlled conditions designed to measure the competitive component of the inhibition) as competitive inhibitors of MAO-A and -B. Adequate correlation of the biological data with the physiochemical constants of substituent groups was obtained only when the m- and p-substituted derivatives were considered separately. Due to the narrow range of activity displayed by the p-substituted derivates when inhibiting MAO-B, meaningful correlations were not found. However, the inhibition of MAO-B by the m-substituted derivatives required the inclusion of the Verloop L parameter for adequate correlation, suggesting that the inhibitor binding site of MAO-B is present within a cavity of more limited lateral dimensions than that present on the MAO-A surface. Inhibition of both MAO-A and -B demonstrated a parabolic relationship between inhibitory activity and pi. Whereas this parabolic relationship showed a maximal value for inhibition of MAO-A (mean pi o = 0.86), inhibition of MAO-B demonstrated a minimal value of pi (pi min = -0.5) i.e. the optimal value of pi for inhibition of MAO-B has not been achieved for this series of compounds but such would be greater than that demonstrated for MAO-A. The Hammett sigma function was important or significant only in the inhibition of MAO-A by the p-substituted derivatives.

Animals↗

PubMed1991

The preparticipation evaluation.

The preparticipation evaluation (PPE) is the first step toward meeting the responsibility of maintaining the health and safety of the athlete. The ideal timing for the PPE is 6 weeks prior to the competitive season to allow adequate time for treatment and rehabilitation of problems. It is suggested that a complete screening evaluation be performed prior to entrance into a new level of school with annual limited reevaluations thereafter. The annual reevaluation should focus on the medical history with the physical examination emphasizing the cardiovascular system and interim injuries and medical problems. Currently, there are no data to support routine screening laboratory, radiographic, or cardiovascular testing in the asymptomatic athlete with an unremarkable history and normal examination. Two different methods for performing the PPE can be used (station-type mass screening and office setting), with each having its own distinct advantages and disadvantages. The most important and difficult decision for the physician screening young athletes is determining clearance for activity. Guidelines based on the demands of the sport and specific medical problems have been established; however, the physician's clinical judgement should be used in interpreting these recommendations for each individual athlete. The PPE is an excellent opportunity for the physician to positively influence the health care and safety of a local sports program. Through genuine interest, thorough evaluation, and knowledgeable counseling, the athlete will develop confidence in the evaluating physician. This confidence can translate into a good relationship and hopefully this interaction will encourage the athlete to trust the physician's judgement and seek early evaluation and treatment for problems that arise.

Health Status↗

PubMed1991

Synovial fluid immunocytology in the diagnosis of leukemic synovitis.

We describe a patient with leukemic synovitis complicating acute lymphoplastic leukemia. Leukemic cells were identified in the synovial fluid by an indirect immunofluorescent technique using monoclonal antibodies against early B cell antigens. Since focal leukemic lesions may be missed in synovial biopsy specimens, immunocytological analysis of joint fluids may facilitate early diagnosis of leukemic arthritis.

Adult↗

PubMed1990

Evaluation of infrared spectroscopy as a bacterial identification method.

A study motivated by the recent revival of interest in the use of IR spectroscopy to identify bacteria is reported. A library of FT-IR spectra of dried bacterial films was complied using 16 different strains. A test set was compiled from spectra of the same strains grown several months later. The test set was quantitatively compared with the library on the basis of spectral similarity in the region 980-1190 cm-1. Six of the strains in the test set were not matched with the correct strain in the library despite efforts to reproduce the conditions under which cells were grown and prepared. The results suggest that reproducibility of the bacterial spectra is a potential difficulty that must be addressed by any attempts to develop FT-IR spectroscopy as a bacterial identification method.

Bacteria↗

PubMed1989

Acute lymphocytosis after trauma--early recognition of the high-risk patient?

An absolute lymphocyte count is included in the routine results provided by most automated blood cell counters, providing a prompt indication of peripheral blood lymphocytosis. Transient lymphocytosis is seen in many acutely ill patients, including those with multiple injuries. We have observed a significantly higher death rate among trauma patients with lymphocytosis at presentation; patients with lymphocytosis, on subsequent assessment of injury, proved to have higher Injury Severity Scores than those without lymphocytosis. Investigation of lymphocyte subsets in nine patients with lymphocytosis showed an increase in T cells, reversal of the CD4:CD8 ratio, and, in seven patients, an increase in "natural killer" cells. The presence of lymphocytosis and its early detection as part of a routine blood count may supply a readily available means of identifying a high-risk trauma patient.

Acute Disease↗

PubMed1988

The effect of nonviral liver damage on the T-lymphocyte helper/suppressor ratio.

In the present investigation an attempt was made to ascertain whether nonviral liver impairment in rats affects the THelper/TSuppressor ratio. Two hepatotoxic agents were used: (i) galactosamine (GA), which causes a drug-induced hepatitis-like damage, and (ii) orotic acid (OA), which induces fatty changes. Since these two substances act as antidotes to one another they were administered to rats either separately or simultaneously. GA caused severe liver damage documented by a 104-, 48-, and 1.6- fold rise in the plasma concentrations of ALT, AST, and ALP and by multiple foci of hepatocyte necrosis. This was followed by a drop in TH/TS ratio from 2.25 observed in the controls to 0.89 in the GA-treated rats. All of these phenomena were prevented by concurrent administration of GA and OA. OA alone did not show an effect on the liver with respect to changes in plasma enzyme concentrations and by light microscopic analysis. However, OA caused a drop in the TH/TS ratio from 2.25 to 1.55. Neither GA nor OA produced a change in TH/TS ratios in in vitro experiments.

Animals↗

PubMed1988

Metabolic heat production of neonatal calves during hypothermia and recovery.

Metabolic heat production and rectal temperature were measured in 19 newborn calves (41.8 +/- 3.7 kg) during hypothermia and recovery when four different means of assistance were provided. Hypothermia of 30 degrees C rectal temperature was induced by immersion in 18 degrees C water. Calves were rewarmed in a 20 to 25 degree C air environment where thermal assistance was provided by added thermal insulation or by supplemental heat from infrared lamps. Other calves were rewarmed by immersion in warm water (38 degrees C), with or without a 40-ml drench of 20% ethanol in water. Resting (prehypothermia) and cold-induced summit metabolism of the calves was 2.5 +/- .1 and 8.2 +/- .22 W/kg and occurred at rectal temperatures of 39.5 +/- .06 and 36.2 +/- .26 degrees C, respectively. During cooling, metabolic heat production declined at the rate of .65 W/kg per degrees C decline in rectal temperature. The time required to regain euthermia from a rectal temperature of 30 degrees C was longer for calves with added insulation and those exposed to heat lamps than for the calves in the warm water and warm water plus ethanol treatments (90 and 92 vs 59 and 63 +/- 6.4 min, respectively). During recovery, the calves rewarmed with the added insulation and heat lamps produced more heat metabolically than the calves rewarmed in warm water. Total heat production during recovery was 34.1, 31.1, 18.3, 16.9 +/- 1.07 kJ/kg for the calves with added insulation, exposed to the heat lamps, in warm water and in warm water plus an oral drench of ethanol, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Lymphocyte surface marker studies in the diagnosis of unexplained lymphocytosis.

Fifty-six patients with unexplained lymphocytosis were investigated with a panel of antibodies to lymphocyte surface antigens. In 23 the distribution of cell surface markers suggested reactive lymphocytosis. The remaining 33 patients showed a distribution of cell surface markers that indicated or suggested a diagnosis of B-cell lymphoproliferative disease. Two illustrative case reports show how such studies performed early in the investigation of unexplained lymphocytosis may permit earlier diagnosis of the underlying mechanism.

Adult↗

PubMed1987

Further characterization of the Krebs tricarboxylic acid cycle metabolon.

A preparation of gently disrupted rat liver mitochondria which shows exposed and easily sedimented Krebs tricarboxylic acid cycle enzyme activities has been characterized further. The exposed malate dehydrogenase is inhibited by high molecular weight blue dextran which indicates the availability of the enzyme to the bulk solvent. Further, mitoplasts are not permeable to citrate synthase antibodies ruling out the possibility of vesicularization of high molecular weight substances. The slightly disrupted mitochondria sedimented more slowly than did intact mitochondria on a Ficoll gradient. Electron microscopy, both thin section and scanning, showed slightly swollen mitochondria with some disruption of the membranes. Labeling with ferritin-labeled second antibody to citrate synthase antibodies showed again the accessibility of these disrupted mitochondria to the antibody. When either the oxidation of fumarate or the malate dehydrogenase-citrate synthase coupled system are studied, relative kinetic advantages are observed of the gently disrupted systems over the completely solubilized system. These kinetic advantages are more labile to disruption than is the binding of the enzymes to the particle. These results indicate that the Krebs tricarboxylic acid cycle exists as a sequential complex of enzymes, a metabolon, in situ. This study shows that previous studies which showed interactions between sequential enzymes of this pathway and their binding to the inner surface of the inner membrane actually reflected an in vivo organization of this pathway.

Animals↗

PubMed1987

Effect of a non-viral fraction of acquired immunodeficiency syndrome plasma on the vulnerability of lymphocytes to cortisol.

We have observed previously that the rate of cortisol catabolism by lymphocytes (CCL) was indicative of the vulnerability of these cells to cortisol. We attempted to ascertain whether cortisol-sensitive lymphocytes (e.g. thymocytes) metabolize cortisol at a different rate from cortisol-resistant cells and whether lymphocytes in which cortisol catabolism is inhibited become cortisol sensitive. The work was facilitated by the observation that an ethanol extract plasma from patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) had the capacity to inhibit CCL. The capacity of thymocytes to metabolize cortisol was found to be 11 times lower than that of peripheral lymphocytes. Inhibition of CCL with an ethanol extract of plasma from AIDS/ARC patients made the cells vulnerable to cortisol, causing them to die at a rate seven times greater than that of control samples. It is suggested that these findings may have important implications with regard to the nature of lymphocyte depletion in AIDS/ARC patients or in people at risk of developing the syndrome.

AIDS-Related Complex↗

PubMed1986

Heat production of cattle acclimated to cold, thermoneutrality and heat when exposed to thermoneutrality and heat stress.

Four Hereford X Red Angus yearling steers were acclimated to each of the following environments; cold (3 C), thermoneutrality (TNZ; 20 C) and heat (35 C). Intake was equalized for all treatments at 4.9 X kg X head-1 X d-1 (2.9 Mcal metabolizable energy/kg). Heat production, respiration rate and rectal temperature were determined after 3- and (21-h later) 24-h exposures to thermoneutral and heat stress test-temperatures: 25, 30, 32.5, 35, 37.5 and 40 C. Thermoneutral heat production (kcal X kg-.75 X d-1), after 3- and 24-h exposures, was greater (P less than .05) for the cold-acclimated cattle (139.6 +/- 5.0 and 153.0 +/- 5.8) as compared with the TNZ-acclimated cattle (117.7 +/- 5.0 and 121.6 +/- 5.8). Heat production of the heat-acclimated cattle after 3- and 24-h exposures to thermoneutrality was 121.0 +/- 5.1 and 123.5 +/- 3.2 and was not different from the TNZ-acclimated cattle. Heat production of steers acclimated to different temperatures was variable during the 3- and 24-h exposures to test-temperatures ranging from 25 to 40 C. Heat production increased linearly in the TNZ-acclimated cattle (24-h exposure) and in the heat-acclimated cattle (3-h exposure) at the rate of 1.3 and 2.3 kcal X kg-75 X d-1 X C-1 increase in test-temperature, respectively. In the other four comparisons, analysis by regression indicated no significant change in heat production. Rectal temperature and respiration rate increased significantly in either a linear or quadratic manner in all treatment groups exposed to test-temperatures from 25 to 40 C.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗