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Biomedical subjects

L Johnson

Publications and source records attributed to L Johnson.

At least 433 records · Page 24Linked to original sources
PubMed1980

Immunological and biochemical analysis of a null mutant of alpha-glycerolphosphate dehydrogenase from Drosophila melanogaster.

A Drosophila null mutant(BO-1-4) of alpha-glycerolphosphate dehydrogenase induced by ethylmethane sulfonate(EMS) was analyzed by double immunodiffusion, enzyme immunoinactivation, immunoelectrophoresis and two-dimensional electrophoresis. Based on all the immunological evidence, this mutant appears to express no protein that can cross-react with the antiserum specific to alpha-glycerolphosphate dehydrogenase. A protein spot corresponding to alpha-glycerolphosphate dehydrogenase was identified on two-dimensional gels of the soluble fly homogenates. The absence of this protein spor on two-dimensional gels of this null mutant further supported the immunological data. The activities of seven other enzymes in the related metabolic pathways were determined for the mutant and the control Drosophila. The null mutant does not show significant alterations in activities of these enzymes. The relationship between the deficiency of this enzyme and the inability for the sustained flight of the null mutant was discussed in terms of cellular metabolic regulations.

Alcohol Oxidoreductases↗
PubMed1980

The relationship of biopsy evaluations and testicular measurements to over-all daily sperm production in human testes.

Enumeration of homogenization-resistant spermatids in testicular homogenates provided a rapid and precise means of characterizing human spermatogenesis in quantitative terms. This technique was applied to simulated biopsy specimens as small as 10 mg of testicular parenchyma and yielded values for daily sperm production per gram of testicular parenchyma (DSP/gm) that were highly correlated with over-all DSP/gm values for paired testes (r = +0.86) and DSP/pair of testes (r = +0.93). In 12 autopsy cases representing a 100-fold range of sperm production rates, the average difference between DSP/gm values obtained from simulated biopsy specimens and from entire testes was not significantly different from zero (P < 0.05). The small amount of testicular parenchyma required for this determination indicated that both DSP data and routine histologic observations can be collected from the material included in a conventional testicular biopsy. Various measurements related to testicular size were positively but weakly correlated with DSP/testis (values for r ranged from +0.45 to +0.66). Hence, testicular size was a relatively poor index of sperm production in this study.

Adolescent↗
PubMed1980

Cerebral Whipple's disease. Diagnosis by brain biopsy.

Whipple's disease, a multisystem chronic granulomatous disease treatable by antibiotics, usually presents clinically with gastrointestinal or joint symptoms. Usually, the diagnosis is substantiated by small intestinal biopsy. This shows diastase-resistant periodic-acid-Schiff-(PAS)-positive inclusions in the cytoplasm of macrophages within the lamina propria. By electron microscopy, this PAS-positive material consists of 1.5 X 0.2-mum bacilli and fine fibrillar material within macrophage phagolysosomes. Rarely, Whipple's disease presents clinically as a primary neurologic disease without gastrointestinal symptoms. Because untreated cerebral Whipple's disease usually progresses rapidly to death, it is imperative to establish the diagnosis promptly. This report describes a case of cerebral Whipple's disease without gastrointestinal symptoms that was diagnosed early by light-and electron-microscopic study of brain biopsy material.

Biopsy↗
PubMed1980

Plasma water and 51Cr EDTA equilibration volumes of different tissues in the rat.

The EDTA space and the plasma water volume of the whole animal and selected tissues were investigated with constant EDTA infusions of different duration in the rat. The calculated EDTA space increased with the duration of the infusion both in the whole animal and the tissues sampled. The plasma water volume remained constant, and therefore the calculated increase of the EDTA space suggests a slow intracellular accumulation of the tracer. As intracellular accumulation of EDTA increases with experimental time, it is necessary to use as short an experimental interval as possible to reduce this error when determining extracellular fluid volumes.

Animals↗
PubMed1980

A pilot study of personality type change.

Three Developmentally Disabled adolescents and three counselors were administered the Myers-Briggs Type Indicator before and after token economy treatment was conducted in a half-way house. The first hypothesis that the personality type scores of the adolescents would become more similar to the personality of the counselors when comparing the pre-test and post-test measures had a proclivity to be supported. The second hypothesis that the personality scores of the adolescents would become more similar to the most extroverted counselor or an overall basis also had a proclivity to be supported. Suggestions for further research are provided.

Acting Out↗
PubMed1980

An autopsy survey of clinical and anatomic diagnoses associated with alcoholism.

Alcoholism, a major cause of hospitalization and death in the United States, has been associated with multiple organ system dysfunctions. A systematic search by computer was made of the diagnoses in 35,579 autopsies performed from 1949 to 1972 at the Los Angeles County-University of Southern California Medical Center. Alcoholic and control cases (total, 8,186) were matched by age, sex, race, and appropriate date of death. Many major differences in diagnosis between the two groups were found. A fourfold increase in the annual frequency of alcoholism at autopsy was noted during the period under study. The mean age at death was ten years less in the alcoholism group compared with the total population submitted to autopsy. This survey supports the hypothesis that the clinical and autopsy diagnosis in alcoholic and nonalcoholic patients are significantly different in frequency.

Adult↗
PubMed1980

Maturation of equine epididymal spermatozoa.

Spermatozoa from four regions of the epididymis and from ejaculated semen were evaluated for their resistance to cold shock, progressive motility, and structural stability. Spermatozoa were incubated at 38 C and their percentage of eosinophilia was compared with that of spermatozoa cooled to 0 C in 2 minutes, 10 C in 12 minutes, or 4 C in 22 minutes. Spermatozoa motility was estimated visually under phase-contrast microscopy and was recorded by cinematography. Structural stability of spermatozoa incubated in 0.05 M sodium borate buffer, 0.035 M sodium dodecyl sulfate (SDS), 0.002 M dithiothreitol (DTT), or SDS+DDT was evaluated by phase-contrast and electron microscopy. The percentage of eosinophilic spermatozoa did not differ among regions of the epididymis and was not increased by cold shock. Cooling ejaculated spermatozoa to 0 C in 2 minutes increased (P < 0.01) the occurrence of eosinophilia (32% vs 73%). Spermatozoa released from the caput or proximal corpus epididymidis into 0.154 M NaCl were not progressively motile; only 4% of the spermatozoa from the distal corpus were motile Cauda epididymal and ejaculated spermatozoa exhibited similar motility (41% vs 47%). Stability of chromatin was greater in spermatozoa from the distal corpus than those from the caput epididymis. Chromatin of spermatozoa from the distal corpus was resistant to 7.5 minutes of SDS+DTT treatment, whereas virtually all spermatozoal nuclei from the caput were decondensed by SDS alone. Tail organelles of spermatozoa acquired stability between the proximal corpus and the cauda epididymidis. All tail organelles of spermatozoa from the proximal corpus were dissolved by 7.5 minutes of SDS treatment, whereas tail organelles of distal corpus epididymal spermatozoa had dissolved after 7.5 minutes of SDS+DTT treatment. Stability of tail organelles in cauda epididymal and ejaculated spermatozoa was similar. Seemingly, equine spermatozoa are infertile until they enter the cauda epididymidis.

Animals↗
PubMed1979

Small hospitals can save on maintenance.

An in-house biomedical equipment maintenance program can be set up in a small hospital at little cost/The benefits of on-call technical aid can be great.

Biomedical Engineering↗
PubMed1979

A classification of retrolental fibroplasia to evaluate vitamin E therapy.

A refined classification of the stages of the retinopathy of prematurity (RLF) based on the experience of over 7500 examinations during the past decade is presented. We have been using the basic elements of this classification since 1972 in order to evaluate the influence of vitamin E on retrolental fibroplasia (RLF). It is our impression that it provides a more accurate clinical method of following the course of the retinopathy and a tool for assessing the factors other than prematurity and hyperoxia that may play a subtle role in the development of RLF.

Humans↗
PubMed1979

Phone rate and the effective planning time hypothesis of stuttering.

Effects on syllable disfluency and phone rate (duration of phones spoken per minute) were compared in 19 adult stutterers under three reading rate conditions: control; slow normally-spoken-word-syllable timed (WS); and phone-prolongation (PP) matched to WS in syllable rate. Both phone rate and syllable disfluency were progressively reduced from control to WS to PP conditions. These results strongly support the discoordination hypothesis that any condition which facilitates initiation of phonation in coordination with articulation and respiration will reduce stuttering. A broader hypothesis is that effective planning time for voice onset coordinations is the common element that explains the power of retarded phone rate, reduction of phonatory complexity, and rhythm virtually to eliminate stuttering.

Adult↗
PubMed1979

Sphenoidal mucoceles with intracranial extension.

Two cases of sphenoid sinus mucocele with intracranial extension are presented. Multiplanar computed tomography scans delineated the extent of these lesions, facilitating both preoperative diagnosis and proper clinical management. One lesion was isodense and the other hyperdense (98 Hounsfield units: 1,000 scale). Neither demonstrated significant enhancement after the administration of contrast medium.

Brain Diseases↗