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Biomedical subjects

S Lewis

Publications and source records attributed to S Lewis.

At least 415 records · Page 23Linked to original sources
PubMed1981

Organization and reorganization of immunoglobulin genes in A-MULV-transformed cells: rearrangement of heavy but not light chain genes.

The structure of immunoglobulin-related gene was analyzed in individual Abelson murine leukemia virus (A-MuLV)-transformed lymphoid cell lines. Essentially all of these lines, whether immunoglobulin-containing or null, had DNA rearrangements in the vicinity of the JH regions on both chromosomes as well as deletions of at least 5 kb of DNA 5' to JH. None of these lines, however, except rare light chain producers, had detectable rearrangement at either their kappa or lambda light chain loci. In contrast to A-MuLV-transformants derived from bone marrow. Those from early fetal liver frequently contained more than two and sometimes 12 or more distinct, rearranged JH-containing fragments. Cellular subclones derived from these lines had a subset, usually two, of the fragments found in the parent line. Therefore, heavy chain gene rearrangement appears to precede that of light chain gene rearrangement and is still continuing in certain cultured A-MuLV transformants.

Abelson murine leukemia virus↗
PubMed1981

Pediatric speech intelligibility test. II. Effect of receptive language age and chronological age.

Performance for Pediatric Speech Intelligibility (PSI) Format I and Format II sentences was significantly different in children between the ages of 3 and 6 years. Performance differences were related to chronological age (CA) and receptive language (RL) ability. However, performance for Format I sentences in children with relatively low RL age and performance for Format II sentences in children with relatively high RL age were equivalent. This observation yielded an algorithm that determines the sentence format as a function of the child's RL age in order to yield 'language equivalent' norms for speech audiometry. Performance for PSI word materials was not influenced by differences in RL skill. CA developmental trends were noted for all speech materials.

Age Factors↗
PubMed1981

Testicular scanning: clinical experience with 72 patients.

Testicular scanning with 99mtechnetium pertechnetate is a well established, useful and readily available technique for the rapid assessment of patients with scrotal pain. Its use allows accurate differentiation of testicular torsion from other entities, such as epididymo-orchitis and, thus, obviates scrotal exploration in a large number of cases. We herein report our experience with 72 cases. Only 1 falsely positive scan was obtained in 15 patients thought to have torsion, this being secondary to an incarcerated hernia extending into the scrotum. Of the remaining 14 patients undergoing scrotal explorations for testicular torsion the scan was accurate in 100 per cent of the cases.

Adolescent↗
PubMed1981

Use of the radionuclide washout test in evaluation of suspected upper urinary tract obstruction.

The use of the computerized quantitative renal scan associated with the standard renogram obtained during furosemide-induced diuresis provides useful information in the assessment of suspected upper tract obstruction. With the use of 99mtechnetium diethylenetriaminepentaacetic acid or 131iodine hippuran quantitative renal scans were obtained and renograms were generated before and after intravenous furosemide injection. Rapidity of diuretic-induced radionuclide washout, as well as determination of glomerular filtration rate or effective renal plasma flow on the affected side, provides objective information with regard to renal parenchymal loss as well as upper tract emptying. We herein report our experience with 19 such patients. The radionuclide washout test is obtained easily, informative and may replace more invasive diagnostic measures.

Child↗
PubMed1981

Studies of the staphylococcal causation of toxic shock syndrome.

The data presented in this study indicate that the Staphylococcus aureus is related casually to the toxic shock syndrome and that the dominant phage type was 29. This type has occurred singly as well as in combination with phage type 52 and some other group I phage types. The 29, 52 complex was present in approximately two-thirds of a series of 159 isolates of Staphylococcus aureus obtained from patients with toxic shock syndrome, while another fourth was nontypable. In further support of this concept was the evidence that 94.1 per cent of the isolates of the 29, 52 phage complex tested were capable of producing pyrogenic exotoxin C. These results gave confirmatory evidence of the etiologic importance of this phage type complex of Staphylococcus aureus. The high percentage of 25.8 per cent nontypable isolated has remained unexplained, and this is suggestive of the possibility that another important phage type may be present but obscure, since 83 per cent were shown to be capable of producing pyrogenic C toxin. The data reported also indicated that the current activity of this phage type is another manifestation of the versatility of Staphylococcus aureus and its ability to produce different pathogenic strains capable of causing different or new infections in clinical practice.

Anti-Bacterial Agents↗
PubMed1981

Cardiac dimensions and performance after either arm or leg endurance training.

We have recently reported improved exercise performance with untrained limbs in 10 men after 11 wk of either arm (N = 5) or leg (N = 5) endurance training. To examine the changes in cardiac function produced by short-term training, we used echocardiography to measure cardiac function at rest, and systolic time intervals (STIs) to measure cardiac function during trained and untrained limb exercise. We repeated all studies after autonomic blockade with atropine and propranolol in order to observe non-autonomic changes in cardiac function. Training had little effect on cardiac size or performance at rest, although with autonomic blockade, cardiac mass increased in the leg-training group and resting left ventricular ejection time (LVET) was prolonged when the two training groups were combined. During submaximal exercise with both trained and undrained limbs and at similar heart rates before and after training, LVET for the combined groups was increased with and without autonomic blockade. This increase in LVET is most consistent with an increased cardiac stroke volume. Short-term endurance training appears to result in improved exercise cardiac function that is in part independent of altered autonomic control or adaptations in trained skeletal muscle.

Adult↗
PubMed1980

Identification and biochemical analysis of mouse mutants deficient in cytoplasmic malic enzyme.

During the biochemical screening of mutant enzymes in mice, individuals with an apparent nonfunctional allele at the locus (Mod-l) responsible for cytoplasmic malic enzyme were identified by starch gel electrophoresis and by enzyme activity measurements. A series of matings and genetic analyses were made, and mice homozygous for the nonfunctional or null allele (Mod-ln) were produced. The mutation appeared to occur spontaneously in the C57BL/6J strain. By double-immunodiffusion and enzyme immunoinactivation assays, the null mutants were shown to express no proteins that cross-react with the antiserum to cytoplasmic malic enzyme (CRM-negative). In liver homogenates of homozygous null mutants, lack of protein components that form complexes with IgG from the cytoplasmic malic enzyme specific antiserum was further demonstrated by passage of the original serum through a mutant liver homogenate--Sepharose column, where the postadsorbed serum retained its titer and specificity. The residual malic enzyme activity (< 10% of the normal) observed in various tissue homogenates of the homozygous null mutants was attributed to that of mitochondrial isozyme of malic enzyme. Assays of enzymes from tissues of different genotypes revealed no significant differences in activities of six other enzymes in the related metabolic pathways. However, in liver from mutant mice, a lower NADPH/NADP+ ratio was consistently observed in comparison to that from control mice. Both the mutant and the control mice of the same age were found to have comparable body weight and lipid content.

Alleles↗
PubMed1980

Anaphylactoid reaction to 50% solution of dextrose.

Two patients with extrinsic asthma and coexistent insulin-dependent diabetes mellitus sustained an anaphylactoid reaction after the intravenous administration of 50% solution of dextrose. Investigations suggested that the dextrose, rather than any additives, was responsible for the reaction. The effect of varying concentrations of dextrose on the histamine content of the blood of normal, allergic, non-diabetic and diabetic, and non-allergic patients was studied. Preliminary results suggest that the higher concentrations of dextrose induce increased histamine release from blood cells, and that this phenomenon is more marked in diabetic, and particularly diabetic-allergic, individuals. We suggest that the treatment of hypoglycaemia with 50% solution of dextrose is associated with a significant risk factor in those diabetic individuals who are either allergic or are receiving beta-adrenoreceptor blocking drugs.

Aged↗
PubMed1980

Pediatric speech intelligibility test. I. Generation of test materials.

Normal children between 3 and 7 years of age generated word and sentence messages for use in a new speech intelligibility test. Word materials did not differ as a function of chronological age, vocabulary skills, or receptive language ability. Sentence materials, however, did reflect differences in chronological age, vocabulary skills, and receptive language skills. Older children, approximately 5-10 years, responded with complete, adult-like sentences. Younger children, approximately 3-10 years, responded with either a proform substituted for the noun phrase subject of a sentence or by omitting the auxiliary verb "be" in forming the present progressive verb tense of the sentence. To represent the differences in the children's responses, two different types of test sentences were formed. In one construction, the test sentence is composed of (noun phrase/verb-ing/noun phrase), preceded by the carrier phrase "show me", e.g., "Show me a bear brushing his teeth". In the other construction, the test sentence is composed of (noun phrase/auxiliary verb-ing/noun phrase), e.g., "A bear is brushing his teeth". The two different sentence forms are proposed as a means of equating differences in normal language development among children.

Age Factors↗
PubMed1980

Increased plasma HDL-cholesterol and apo A-1 in sedentary middle-aged men after physical conditioning.

Previous studies have demonstrated an inverse relationship between plasma high density lipoproteins (HDL) cholesterol and coronary heart disease risk. In the present study we investigated prospectively the effect of a moderate physical conditioning programme on plasma lipids and lipoproteins, especially HDL-cholesterol and apolipoprotein A-I (apo A-I), the major apoprotein of HDL. Healthy, sedentary, middle-aged men were randomly selected and assigned either to a training group (n = 24, age 40 +/- 3.4, mean +/- SD) or to a control group (n = 13, age 39 +/- 5.0). Training consisted of various indoor and outdoor sports activities 45 min/day, 3 times/week for 12 weeks at an intensity of approximately 80% of measured maximal oxygen uptake (VO2 max). The trained subjects were studied at 4, 8 and 12 weeks. The training increased VO2 max by 12% (P less than 0.01). Increases were observed in both apo A-I (10%, P less than 0.02) and HDL-cholesterol (8%, P less than 0.02) after training, with significant increases already after 4 and 8 weeks, respectively. Furthermore, decreases in total plasma cholesterol (5%, P less than 0.004) and plasma triglycerides (26%, P less than 0.003) were found without changes in body weight, body composition, cigarette smoking, alcohol consumption or the percentage composition of dietary intake. Fasting serum-insulin concentrations decreased significantly during training. No changes were noted in the control group. The present study demonstrates prospectively that moderate physical training can increase HDL.

Adult↗
PubMed1980

Control of repetitive firing in squid axon membrane as a model for a neuroneoscillator.

1. Repetitive firing in space-clamped squid axons bathed in low Ca and stimulated by a just suprathreshold step of current can be annihilated by a brief depolarizing or hyperpolarizing pulse of the proper magnitude applied at the proper phase. 2. In response to such perturbations, membrane potential and ionic currents show damped oscillations toward a steady state. 3. For other, non-annihilating, perturbations repetitive firing resumes with unaltered frequency but with phase resetting. 4. Experimental findings are compared with calculations for the space-and current-clamped Hodgkin-Huxley equations. Annihilation of repetitive firing to a steady state corresponds to a solution trajectory perturbed off a stable limit cycle and into the domain of attraction of a coexistent stable singular point. 5. Experimentally and theoretically the nerve exhibits hysteresis with two different stable modes of operation for a just suprathreshold range of bias current: the oscillatory repetitive firing state and the time-independent steady state. 6. Analogy is made to a brief synaptic input (excitatory or inhibitory) which may start or stop a biological pace-maker.

Action Potentials↗