Search PubMed⌕ Search

Biomedical subjects

J R Fischer

Publications and source records attributed to J R Fischer.

89 records · Page 5Linked to original sources
PubMed1979

Blood pressure variability of the individual in orthostatic testing.

Within-subject blood pressure (BP) variability was studied in the context of orthostatic testing. Nineteen healthy men volunteered for biweekly orthostatic testing. BP's were taken on alternate minutes during 5 min of supine rest and a subsequent 5 min of quiet standing. Within-subject variance was computed for systole and diastole by protocol condition; respective variances were than pooled (i.e. averaged) across subjects. The within-subject estimate of variance for a single BP reading in either position was approximately 6 torr (i.e. 1 S.D.). This variance estimate was reduced by averaging additional BP readings from the same visit, and more so by averaging BP readings from multiple visits. These findings have use in the design of orthostatic protocols and in the interpretation of BP data derived therefrom.

Adult↗
PubMed1978

On internal electron transfer in xanthine oxidase.

The structural basis for intramolecular electron transfer in xanthine oxidase (EC 1.2.3.2) has been probed using temperature-jump perturbation and optical spectroscopic methods. Redox equilibria were found to be temperature-insensitive; hence it is argued that electron transfer is not accompanied by any extensive macromolecular conformational changes. No evidence for absorption phenomena ascribable to optical electron transfer could be found throughout the course of reductive titration of the biological particle. The combined results suggest that long-range electron transfer in the xanthine oxidase can best be described as occurring between only weakly interacting redox sites embedded in a rigid protein matrix.

Animals↗
PubMed1978

Medium for the enumeration and isolation of bacteria from a Swine waste digester.

A habitat-simulating medium was developed for the enumeration and isolation of bacteria from a swine waste digester. A roll tube medium with growth factors for strict anaerobes from previously studied anaerobic ecosystems was used to evaluate the effects of deletion, addition, or level of digester fluid, digester fluid treated with acid or base, rumen fluid, fecal extract, anaerobic pit extract, tissue extract, carbohydrates, peptones, short-chain fatty acids, minerals, vitamins, N and P sources, reducing and solidifying agents, buffers, and gases on colony counts. Decreasing the agar concentration from 2.5 to 1.0% increased the counts twofold. Blending increased the counts 1.7-fold. With a medium (174) containing digester fluid, peptones, minerals, cysteine, sodium carbonate, and agar, colony counts were 60% of the microscopic count and improved yields 2.5 to 20 times those obtained with media previously used for digesters or developed for other anaerobic ecosystems. Colony counts continued to increase for up to 4 weeks of incubation. Medium 174 permits the enumeration of total, methanogenic, and, with deletion of reducing agent, aerotolerant bacteria. The results suggest that the predominant bacteria grow slowly and have requirements different from those of bacteria from other ecosystems.

Journal Article↗
PubMed1978

Pregnancy after jejunoileal bypass and the SGA infant.

Twenty-one pregnancies (19 patients) were studied, noting the effects of previous jejunoileal bypass on perinatal sequelae. A larger percentage of SGA infants (20%) were delivered to mothers after bypass surgery. Low birthweight appears to be related to maternal hypoalbuminemia. Twelve of thirteen (92%) infants born to multiparous patients after surgery had term birthweights less than any previous term infant's birthweight prior to the procedure. Postponement of pregnancy after ileal shunt until all metabolic parameters have returned to normal (up to 36 months) is advised.

Adult↗
PubMed1976

Characterization of a cell-lethal product from the photooxidation of tryptophan: hydrogen peroxide.

Near-ultraviolet (300 to 400 nanometers) irradiation of saturated, oxygenated solutions of tryptophan in the absence of added sensitizer gives rise to substances that have various biological effects on isolated cells, including mutagenicity and selective lethality to recombination-deficient bacterial mutants. One of these biologically active products has been identified as H2O2, on the basis of spectrometric, chromatographic, chemical, and biological properties. Now H2O2 has been shown to account for the biological activities mentioned above.

Escherichia coli↗
PubMed1976

The effect of aging on the impact resistance of heat tempered lenses.

Stock sperocylindrical lenses (125) with approximately 2.2-mm center thickness were bevel-edged to 48-mm size in the S-10 standard military lens shape. One time each, 25 lenses were drop balled directly after heat treatment; 25 after 3 months;25 after 6 months; 25 after 9 months; and the final 25 after 1 year. Comparing these samples against each other showed no statistical difference in breakage. All the surviving lenses were then drop balled repeatedly until broken or 25 impacts had been made. After 25 hits, 76.8% of the lenses did not break. There was no statistical difference in breakage when these results were compared with 125 heat-treated lenses of similar specifications that were drop balled for 25 trials, if not broken sooner, just after routine heat-treatment processing. Lenses of approximately 3.0-mm center thickness, with other aspects the same, were also treated. The effect of drop balling nonheat-tempered lenses of dimensions similar to the aged lenses was studied; the first drop had a casualty rate of 75%, and no lens survived more than 8 impacts.

Eyeglasses↗
PubMed1975

Membrane filter technique for enumeration of enterococci in marine waters.

A membrane filter procedure is described for the enumeration of enterococci in marine waters. The procedure utilizes a highly selective and somewhat differential primary isolation medium followed by an in situ substrate test for identifying colonies of those organisms capable of hydrolyzing esculin. The procedure (mE) was evaluated with known streptococci strains and field samples with regard to its accuracy, sensitivity, selectivity, precision, and comparability to existing methods. Essentially quantitative recovery was obtained with seawater-stressed cells of Streptococcus faecalis and S. faecium. Neither S. bovis, S. equinus, S. mitis, nor S. salivarius grew on the medium. The selectivity of the medium was such that a 10,000-fold reduction in background organisms was obtained relative to a medium which contained no inhibitors and was incubated at 35 C. About 90% of those typical colonies designated as enterococci confirmed as such and about 12% of the colonies not so designated were, in fact, identified as enterococci. Plate to plate variability across samples approximated that expected by chance alone. Verified recoveries of enterococci from natural samples by the mE procedure, on the average, exceeded those by the KF method by one order of magnitude.

Cell Count↗
PubMed1974

Quantitative large-volume sampling technique.

A filtration technique for high-volume sampling of water has been developed that, when combined with the most probable number procedure, permits the quantitation of microorganisms present at very low densities.

Bacteriological Techniques↗
PubMedDate not supplied

Functional urethral obstruction in 3 dogs: clinical and urethral pressure profile findings.

Three dogs with dysuria and urine retention caused by excessive functional urethral resistance are described. All dogs had clinical histories and urologic signs that previously would have been classified as detrusor-urethral dyssynergia. Diagnosis of functional urinary obstruction was established by exclusion of anatomic urinary obstruction and confirmed by urethral pressure profilometry. In 2 cases, multiple pressure deflections recorded in the urethral pressure profile suggested spasm of urethral musculature, whereas in a 3rd dog, abnormally high pressures were recorded along a portion of the proximal urethra. Functional urinary obstruction was associated with prostatitis in 1 dog and with a history of urethral calculi in 1 dog, and no underlying disorder could be identified in the remaining dog. All 3 dogs improved with medical treatments that included alpha adrenergic antagonists. The etiology, diagnosis, and pharmacologic management of functional urinary obstruction are discussed.

Animals↗
PubMedDate not supplied

Mycoplasmal conjunctivitis in wild songbirds: the spread of a new contagious disease in a mobile host population.

A new mycoplasmal conjunctivitis was first reported in wild house finches (Carpodacus mexicanus) in early 1994. The causative agent was identified as Mycoplasma gallisepticum (MG), a nonzoonotic pathogen of poultry that had not been associated with disease in wild songbirds. Since the initial observations of affected house finches in the mid-Atlantic region, the disease has become widespread and has been reported throughout the eastern United States and Canada. By late 1995, mycoplasmal conjunctivitis had spread to an additional species, the American goldfinch (Carduelis tristis). This new disease exemplifies the rapid spread of a pathogen following introduction into a mobile wildlife population and provides lessons that may apply to emerging human diseases.

Animals↗
PubMedDate not supplied

Glucagon constant-rate infusion: a novel strategy for the management of hyperinsulinemic-hypoglycemic crisis in the dog.

A six-year-old, spayed female, cocker spaniel was presented for hypoglycemic seizures. Hypoglycemia with concomitant hyperinsulinemia suggested an insulin-secreting tumor. Pancreatic masses were resected, and insulinoma was diagnosed. Six weeks later, the dog presented in hyperinsulinemic-hypoglycemic crisis (HHC). The dog was initially stabilized with intravenous dextrose boluses and infusions, but seizure activity recurred and persisted. A glucagon constant-rate infusion (GCRI) was initiated, and neurological signs quickly resolved. Dextrose was withdrawn over 24 hours, and euglycemia was maintained by GCRI alone. Despite aggressive medical management including the use of prednisone, diazoxide, bovine somatotropin, and streptozocin, the dog presented on two subsequent occasions in HHC and both times was rapidly stabilized with GCRI alone. In this dog, GCRI was a fast, safe, and effective method of achieving and maintaining euglycemia despite intractable hyperinsulinism. The clinical use of GCRI merits further investigation for management of HHC in veterinary species.

Animals↗
PubMedDate not supplied

Mycoplasma gallisepticum in house finches (Carpodacus mexicanus) and other wild birds associated with poultry production facilities.

Since 1994, an epidemic of conjunctivitis caused by Mycoplasma gallisepticum (MG) has spread throughout the eastern population of house finches (Carpodacus mexicanus). The adaptation of MG to a free-flying avian species presents potential problems for the control of mycoplasmosis in commercial poultry. To evaluate risks associated with this emerging problem, a field survey was conducted to assess prevalence of MG infection in house finches and other passerine birds associated with poultry farms. Between November 1997 and March 1999, 1058 birds were captured by mist net or trap at 17 farms and at 10 feeder stations in northeast Georgia. Birds were bled and screened by serum plate agglutination (SPA) for antibodies to MG. Birds with negative or weak positive SPA results were released at capture sites, and those with strong positive SPA reactions were kept for further evaluation. Necropsies were performed on selected house finches and individuals of 11 other passerine species, and samples were collected for MG testing by culture, polymerase chain reaction (PCR), hemagglutination inhibition, and histopathology. Testing revealed 19.1% of 671 birds caught at farms and 11.6% of 387 birds caught at feeder sites were SPA positive for MG. Three house finches captured on farms were positive for MG by culture and PCR, whereas three from feeder sites were positive only by PCR. No MG isolates were made from tufted titmice (Baeolophus bicolor), but 40% were positive by PCR. Individuals from 10 additional species were SPA positive only. Results suggest that MG persists at low levels in house finches in northeast Georgia and that tufted titmice may be nonclinical carriers of MG or a related mycoplasma. Positive SPA reactions in other species may be caused by nonspecific reactions or contact exposure. Current biosecurity recommendations should be sufficient to minimize risks of transmission between wild and domestic birds.

Agglutination Tests↗
PubMedDate not supplied

Autocrine growth factors secreted by the malignant human B-cell-line BJAB are distinct from other known cytokines.

BJAB, a EBV-negative Burkitt-like lymphoma, did not grow under suboptimal culture conditions in low concentrations of serum unless appropriate cytokines were added. A subclone of BJAB, Clone 13, however, could be kept in long-term culture under such conditions without added cytokines. This suggested that growth of BJAB-Clone 13 was supported by autocrine growth factors (AGF). In fact, the supernatant of Clone 13 stimulated growth of the parental BJAB line and showed IL-1-like activity. Of several cytokines tested only AGF and IL-1 stimulated growth of BJAB. IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, GM-CSF, TNF-alpha, LT, IFN-gamma and TGF beta did not have this effect. The IL-1-like activity was completely neutralized by anti-IL-1 alpha antibodies. In contrast, AGF-activity was not affected by anti-IL-1 alpha. Rabbit antibodies produced against fractions enriched for AGF inhibited growth of BJAB. This inhibition was overcome by Clone 13-AGF, but not by IL-1 alpha. These data suggest that Clone 13-AGF is distinct from IL-1 alpha and might be a new cytokine.

Antibodies↗
PubMedDate not supplied

Field investigation of Mycoplasma gallisepticum infections in house finches (Carpodacus mexicanus) from Maryland and Georgia.

A field study investigating the occurrence of Mycoplasma gallisepticum (MG) in house finches (Carpodacus mexicanus) was conducted in Maryland and Georgia. Eighty-eight finches were captured and examined grossly and microscopically for MG-related conjunctivitis. Serum samples were obtained for serum plate agglutination (SPA) and hemagglutination inhibition (HI) testing. Swabs from conjunctiva, sinus, and choanal cleft were inoculated into two mycoplasma broth media for culture and polymerase chain reaction (PCR) testing. From Maryland, 12 of 57 birds examined had gross conjunctival lesions. MG was isolated from 9 of the 12 affected birds and from three birds without gross lesions. Fourteen of 22 finches tested by PCR were positive for MG. Sixteen of 38 birds were positive for MG by SPA, and 9 of these had HI titers of 1:40 or 1:80. From Georgia, 3 of 31 finches examined had gross lesions; two of these were both culture and PCR positive for MG. Twelve birds were positive by SPA, and two of these had HI titers of 1:80. Histologic findings in birds with gross conjunctivitis from both locations were characterized by extensive epithelial and lymphoid hyperplasia as well as lymphoplasmacytic inflammation in conjunctival tissues; keratitis was rarely present. The source of MG infection in house finches is unknown, and further research is warranted to determine the prevalence and impact of this newly described disease.

Agglutination Tests↗
PubMedDate not supplied

Potential for transmission of the finch strain of Mycoplasma gallisepticum between house finches and chickens.

Although Mycoplasma gallisepticum (MG) is established in house finch (Carpodacus mexicanus) populations in at least 33 states, the potential risk of MG introduction to domestic poultry by infected finches currently is unknown. The objectives of this study were to determine if chickens could be infected with the finch strain of MG via direct, across-wire, and proximity (across-room) contact with naturally infected house finches and to determine if house finches could be infected through direct contact with experimentally infected chickens. Chickens were infected with the finch strain of MG through direct contact with naturally infected house finches, a determined by seroconversion (80%), polymerase chain reaction (PCR) (20%), and culture of MG (30%). Clinical disease was not observed in infected chickens. Isolates from chickens were identified as the original finch strain by arbitrary primed PCR. Transmission required an extended period of direct contact (10 wk) with infected finches, and no evidence of MG infection was detected in chickens exposed to infected finches across wire or across the room. Evidence of contact transmission of MG from infected chickens to house finches was limited to positive serum plate agglutination results, and infection could not be confirmed by PCR or culture. Results suggest that minimal biosecurity measures that restrict direct contact between chickens and house finches should significantly reduce the potential for MG transmission between these species.

Animals↗