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Biomedical subjects

S Newman

Publications and source records attributed to S Newman.

At least 127 records · Page 7Linked to original sources
PubMed1988

Cerebral blood flow during cardiopulmonary bypass.

In a study of the cerebral consequences of cardiopulmonary bypass (CPB), we have assessed cerebral blood flow (CBF) by intra-arterial Xenon 133 clearance, utilising a Novocerebrograph 10a, before, during and immediately following CPB. All patients (n = 51), under the care of a single surgical team underwent elective coronary revascularisation using a standardised anaesthetic and surgical protocol. CBF, measured as the initial slope index (ISI), fell significantly from before (median 22.5) to on bypass (median 20) (Wilcoxon P less than 0.005) and was significantly increased in the immediate post-bypass period (median 28) compared with pre-bypass (Wilcoxon P less than 0.001). Scattergrams reveal CBF to be independent of arterial pressure (BP) but show an important relationship between arterial PaCO2 and CBF. The correlations between PaCO2 and CBF prior to bypass (r = 0.46 P less than 0.005) and post-bypass (r = 0.46 P less than 0.001) are very similar, whilst on bypass, the correlation, although remaining significant, is reduced (r = 0.31 P less than 0.02). The median values for arterial PaCO2 are low throughout the study (pre-bypass median 33 mmHg, on bypass median 28 mm Hg and post-bypass median 36 mm Hg). The maintenance of PaCO2 within the normal range of 35-45 mm Hg may minimise the risk of low CBF due to hypocarbia which could theoretically be harmful in patients known to be at risk of both short term and long term cerebral dysfunction.

Carbon Dioxide↗
PubMed1988

An alternative approach for statistical analysis of kidney transplant data: multivariate analysis of single-center experience.

To avoid the center effect and the possible hidden interactions of multicenter studies, the validity of the Cox Proportional Hazards Model for the analysis of a single-center kidney transplant program was tested, considering 287 renal transplants performed in a 10-year period. The inclusion of type of donor and main immunosuppressive drug as covariates in the model did not violate the proportionality assumption of the Cox model. According to this method, the following covariates were significant in predicting graft survival: cyclosporine, type of donor, good human leukocyte antigen (HLA)-A and HLA-B match (DR data were not considered), highest percentage of reactive antibodies against panel cells, and nephroangiosclerosis as a primary renal disease. Cyclosporine did not significantly improve graft survival in living related donor transplants. Pretransplant blood transfusions, cold ischemia time, and donor ABO blood group were initially significant but dropped out in the step-down procedure. Recipient's age at transplant, cyclosporine, HLA-A and HLA-B match, and nephroangiosclerosis were significant in predicting patient survival. It was concluded that using long-term data of cadaveric and living related renal transplants either on azathioprine or cyclosporine is a valid way to perform multivariate analysis of single-center transplant programs that do not have large samples.

Adult↗
PubMed1988

Genetic divergence in mandible form in relation to molecular divergence in inbred mouse strains.

Genetic divergence in the form of the mandible is examined in ten inbred strains of mice. Several univariate and multivariate genetic distance estimates are given for the morphological data and these estimates are compared to measures of genealogical and molecular divergence. Highly significant divergence occurs among the ten strains in all 11 mandible traits considered individually and simultaneously. Genealogical relationship among strains is highly correlated with genetic divergence in single locus molecular traits. However, the concordance between genealogical relationship and multivariate genetic divergence in morphology is much more complex. Whether there is a significant correlation between morphological divergence and genealogy depends upon the method of analysis and the particular genetic distance statistic being employed.

Animals↗
PubMed1988

Optimization of respiratory muscle relaxation during mechanical ventilation.

The authors calculated the active work of inspiration (Wp) and the inspiratory muscle pressure-time product (integral of Pmus.dt) in seven patients undergoing mechanical ventilation (MV). This was done by comparing the areas under the inflation pressure-volume and inflation pressure-time curves generated when the patient was contributing to the work of ventilation with those following sedation, when inspiratory muscle activity was absent (defined as absence of diaphragmatic EMG activity and of palpable accessory muscle contraction). Inspiratory muscle inactivity could be predicted by the observation of a smooth rise in inflation pressure that was highly reproducible from breath to breath. Relaxation was present without sedation during MV in the control mode with inspiratory flow rates above 65 1/min. In the assist mode (AMV), both Wp and integral of Pmus.dt were significantly (P less than 0.05) greater than in the control (CMV) mode. Reducing trigger sensitivity during AMV further increased Wp and integral of Pmus.dt (P less than 0.05). During AMV and CMV Wp and integral of Pmus.dt decreased with increasing rate of inspiratory flow delivered by the ventilator. With AMV at low trigger sensitivity and low flow rates, Wp approached 65% of the total inspiratory work. The authors conclude that inspiratory muscle activity can be substantial during MV, particularly during AMV at low trigger sensitivity and flow. Monitoring of inflation pressure is a simple means of determining the degree of inspiratory muscle rest during MV.

Humans↗
PubMed1988

The radiobiology of 24 keV neutrons. Measurement of the relative biological effect free-in-air, survival and cytogenetic analysis of the biological effect at various depths in a polyethylene phantom and modification of the depth-dose profile by boron 10 for V79 Chinese hamster and HeLa cells.

HeLa human carcinoma cells and V79 Chinese hamster fibroblasts have been irradiated in vitro with a beam of neutrons with a nearly pure 24 keV spectrum. The relative biological effectiveness (RBE) of the filtered neutron beam relative to 60Co gamma radiation was determined by irradiation of cell cultures "free-in-air". The values obtained for the RBE at 37% survival were 5.8 +/- 0.8, at a dose of 0.69 +/- 0.06 Gy for the HeLa cells and 3.14 +/- 1.1 at a dose of 1.09 +/- 0.091 Gy for the V79 cells. Cytogenetic analysis of the damage in irradiated V79 cells gave an RBE of 6.7 +/- 1.4. Irradiation in a polyethylene phantom markedly attenuated the beam's biological effect. For both cell lines 2 cm of polyethylene virtually eliminated cell killing. Addition of boron 10 to the medium led to increased cell killing and a value of 4 was obtained for the RBE of the 10B(n, alpha)7Li reaction in HeLa cells.

Animals↗
PubMed1987

Identification of a cDNA coding for a fifth form of myelin basic protein in mouse.

The primary sequences of four molecular mass variants (14, 17, 18.5, and 21.5 kDa) of the mouse myelin basic protein (MBP) have recently been determined through analysis of cDNA clones of their mRNAs. The mRNAs coding for the four MBP variants are thought to arise by differential splicing of two exons (exons 2 and 6) from a single gene. In contrast, exons 2 and 5 may be spliced out in the posttranscriptional processing of the human MBP gene. To investigate the possibility that a third exon (exon 5) may also be differentially spliced out in the processing of the mouse MBP gene transcript, a mouse cDNA library was screened to search for cDNAs missing exon 5. A MBP cDNA was isolated whose coding region specified a fifth mouse MBP variant with a molecular mass of approximately equal to 17 kDa. The mass of this variant (17,257 Da) is so close to that of the other 17-kDa mouse MBP (17,224 Da) that the two would be indistinguishable on NaDodSO4/polyacrylamide gels. Analysis of the sequence of the cDNA clone indicates that excision of exons 2 and 5 of the mouse MBP gene would produce the mRNA encoding this newly described 17-kDa MBP, whereas excision of exon 6 would produce the mRNA for the other 17-kDa MBP variant. Thus, the "17-kDa" mouse MBP consists of at least two molecular forms with very similar molecular masses but markedly different primary sequences. Of five full-length or near full-length cDNAs representing 17-kDa MBPs, one was missing exons 2 and 5 and four were missing exon 6.

Amino Acid Sequence↗
PubMed1987

Effect of hyperinflation and equalization of abdominal pressure on diaphragmatic action.

We tested the hypothesis that the mechanical arrangement of costal (COS) and crural (CRU) diaphragms can be changed from parallel to series when direct or indirect transmission of tension occurs. Ratio of rib cage to abdominal displacement (RC/AB) resulting from separate COS and CRU stimulations were used to measure RC expanding action. Hyperinflation in six dogs caused RC/AB with COS and CRU stimulations to change progressively from 0.53 +/- 0.07 (SE) and 0.03 +/- 0.05 at functional residual capacity (FRC) to -0.48 +/- 0.08 and -0.46 +/- 0.05 at 68% inspiratory capacity, respectively. Liquid substitution of abdominal contents in six other dogs equalized abdominal pressure swings (delta Pab), without changing chest wall elastic properties or geometry, or costal RC/AB (0.35 +/- 0.07 before and 0.33 +/- 0.06 after) but caused crural RC/AB to change from 0.01 +/- 0.05 to 0.31 +/- 0.01. We conclude that hyperinflation changes fiber orientation, allowing direct transmission of tension between COS and CRU, which become linked mechanically in series (the diaphragm acts as a unit with RC deflating action); and equalization of delta Pab causes indirect transmission of tension between COS and CRU, which become linked in series (the diaphragm acts as a unit with RC inflating action).

Abdomen↗
PubMed1987

Olfactory bulbs influence testosterone feedback on gonadotropin secretion in male hamsters on long or short photoperiod.

Previous studies have shown that prepubertal olfactory bulbectomy will prevent the testicular regression associated with short photoperiod in golden hamsters. The gonadal regression which normally occurs in hamsters on short photoperiod is known to be due in part to an increased responsiveness of the reproductive neuroendocrine system to the negative feedback actions of testosterone on LH and FSH secretion. The present study tested whether the olfactory bulbs influence the feedback effects of testosterone on gonadotropin secretion. Twenty-four- to 26-day-old male golden hamsters were either olfactory-bulbectomized (BX) or sham-olfactory-bulbectomized. Eight weeks later, all hamsters were castrated, and one half of each group was placed in LD 10:14 (this was called week-8 of the study), while the other half was returned to long photoperiod (LD 14:10). Eight weeks following castration (week 0 of the study), all animals were implanted with silastic capsules containing 0, 4, 8 or 16 mm of testosterone. All hamsters were bled by cardiac puncture at -8, -4, 0, +2, +4, +6 and +8 weeks. The concentration of LH and FSH in these samples was then determined by RIA. BX completely prevented the negative feedback of testosterone on gonadotropin secretion in hamsters on either long or short photoperiod at all levels of testosterone tested in this study. In addition, there were seemingly steroid-independent effects of BX on gonadotropin levels in the castrated hamsters prior to testosterone replacement at weeks -4 and 0.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Surveillance of work-related cold injuries using workers' compensation claims.

The usefulness of workers' compensation claims for the surveillance of occupational injuries was evaluated by analyzing claims for cold injury. Five hundred ten claims filed in 1983 from 23 states participating in the Bureau of Labor Statistics Supplementary Data System and an additional 147 claims filed with the Division of Safety and Hygiene of the Industrial Commission of Ohio from Jan 1, 1984, to June 30, 1985, were examined. As expected, the number of injuries per winter day increased as temperature decreased and wind speed increased. The rate of injury began to increase when temperatures fell below 10 degrees F and wind speeds exceeded 10 mph. These weather conditions were milder than previously published cold hazard charts suggest. Frostbite injuries of the lower extremities occurred at milder temperatures, required more lost workdays, and were more costly than cold injuries to the head and face or to the upper extremities. Industries with the highest rates of injury included agriculture, oil and gas extraction, trucking and warehousing, protective services, and interurban transportation. Injuries during nonwinter months involved the processing, distribution, and preparation of food. Vehicle breakdown or contact with water, gasoline, alcohol, or cold water were noted as contributing factors on many of the compensation claims. This probe suggests that claims for workers' compensation adequately reflect the expected association of environmental factors and the occurrence of cold injury.

Absenteeism↗
PubMed1986

The potential of carboxypeptidase G2-antibody conjugates as anti-tumour agents. I. Preparation of antihuman chorionic gonadotrophin-carboxypeptidase G2 and cytotoxicity of the conjugate against JAR choriocarcinoma cells in vitro.

Carboxypeptidase G2, a zinc metalloenzyme isolated from Pseudomonas sp. strain RS-16, which catalyses the hydrolytic cleavage of reduced and non-reduced folates to pteroates and L-glutamate, has been linked to a monoclonal antibody (W14A) raised to human chorionic gonadotrophin. The coupling efficiency and retention of antibody and enzymatic activities are compared for three separate methods of preparing 1:1 conjugates. Preliminary in vitro studies on the cytotoxicity of the free enzyme and the conjugated enzyme towards JAR choriocarcinoma cells are reported. Despite the limitations of the in vitro model, it could be demonstrated that a significant proportion of 10(6) choriocarcinoma cells lost viability when exposed to either free or conjugated enzyme for 72 hours at concentrations of carboxypeptidase G2 of 1-3 units ml-1 of medium.

Antibodies, Monoclonal↗
PubMed1986

In vivo length-force relationship of canine diaphragm.

Diaphragmatic length was measured by sonomicrometry and transdiaphragmatic pressure (Pdi) by conventional latex balloons in eight dogs anesthetized with pentobarbital sodium under passive conditions and during supramaximal phrenic stimulation. The passive length-pressure relationship indicates that the crural part of the diaphragm is more compliant than the costal part. With supramaximal stimulation the costal diaphragm showed a length-pressure relationship similar in shape to in vitro length-tension curves previously described for the canine diaphragm. The crural part has a smaller pressure-length slope than the costal part in the length range from 80% of optimum muscle length (Lo) to Lo. At supine functional residual capacity (FRC) the resting length (LFRC) of the costal and crural diaphragms are not at Lo. The costal part is distended to 105% of Lo, and crural is shortened to 92% of Lo. Tidal shortening will increase the force output of costal while decreasing that of the crural diaphragm. The major forces setting the passive supine LFRC are the abdominal weight (pressure) and the elastic recoil of the lungs. The equilibrium length (resting length of excised diaphragmatic strips) was 79 +/- 3.6% LFRC for the costal diaphragm and 87 +/- 3.9% LFRC for the crural diaphragm. Similar shortening was obtained in the upright position, indicating passive diaphragmatic stretch at supine LFRC.

Animals↗
PubMed1986

Newborn screening for hemoglobinopathies: the benefit beyond the target.

As a result of New York State's Newborn Screening Program 4,565 neonates with trait hemoglobinopathies were identified and 3,200 families were notified of the results of testing their infants in New York City in 1982. Of the 1,531 families (2,190 parents) tested and counseled, 22 parents were diagnosed with sickle cell disease and 39 couples were found to be at-risk for having a child with sickle cell disease. Amniocentesis was performed in 14 of the 28 at-risk pregnant women and three of the four affected pregnancies were terminated. MCH-331001-01 to 04

Anemia, Sickle Cell↗