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Biomedical subjects

J Smith

Publications and source records attributed to J Smith.

At least 775 records · Page 43Linked to original sources

Survival after total body irradiation: effects of irradiation of exteriorized small intestine.

Rats receiving lethal irradiation to their exteriorized small intestine with pulsed 18 MVp bremsstrahlung radiation live about 4 days longer than rats receiving a dose of total-body irradiation (TBI) causing intestinal death. The LD50 for intestinal irradiation is approximately 6 Gy higher than the LD50 for intestinal death after TBI. Survival time after exteriorized intestinal irradiation can be decreased, by adding abdominal irradiation. Adding thoracic or pelvic irradiation does not alter survival time. Shielding of large intestine improves survival after irradiation of the rest of the abdomen while the small intestine is also shielded. The kinetics of histological changes in small intestinal tissue implicate the release of humoral factors after irradiation of the abdomen. Radiation injury develops faster in the first (proximal) 40 cm of the small intestine and is expressed predominantly as shortening in villus height. In the last (distal) 40 cm of the small intestine, the most pronounced radiation effect is a decrease in the number of crypts per millimeter. Irradiation (20 Gy) of the proximal small intestine causes 92% mortality (median survival 10 days). Irradiation (20 Gy) of the distal small intestine causes 27% mortality (median survival greater than 30 days). In addition to depletion of crypt stem cells in the small intestine, other issues (humoral factors, irradiated subsection of the small intestine and shielding of the large intestine) appear to influence radiation-induced intestinal mortality.

Animals↗

Acute open reduction and rigid internal fixation of proximal interphalangeal joint fracture dislocation.

We report the application and results of a technique of open reduction and rigid internal fixation of dorsal fracture/dislocation of the proximal interphalangeal joint with an interfragmentary screw in two cases. Articular congruity was restored, and the proximal interphalangeal joint was stabilized. This technique permitted immediate range-of-motion exercises. Excellent results were obtained in both cases. Previous descriptions have not detailed the indications, the surgical approach, or the results of this technique.

Adolescent↗

Laboratory profile of sickle cell disease: a cross-sectional analysis. The Cooperative Study of Sickle Cell Disease.

We have collected steady-state laboratory data for over 2600 patients, age 2 years and over, with sickle cell anemia (HbSS), HbSC disease, and HbS-beta(+)-thalassemia. The packed cell volume (PCV) is lower in males than in females until 17 or 18 years of age in HbSS and ages 13 to 15 in HbSC, but then becomes consistently higher in males. After age 40, the PCV falls in HbSS. The steady-state leukocyte count in HbSS is higher than that in normals, blunting the utility of this measurement in the assessment of infection. In HbSC and HbS-beta(+)-thalassemia, the leukocyte counts are more often within the range of normal. Platelet counts in HbSS are often found to be above normal and show a downward trend with age. There is a progressive rise in creatinine with age. In HbSS, this rise begins at age 14 and may be accounted for by the increased muscle mass that occurs with puberty. The further deterioration of renal function in patients over 20 may be a result of the known adverse effects of sickle cell disease upon the kidney. Our data provide a basis to compare perturbations caused by intercurrent complications and new therapies, as well as to contrast with similar information from other populations of patients with sickle cell disease.

Adolescent↗

Wisdom-related knowledge in a life review task: age differences and the role of professional specialization.

The study adopts life review as an avenue to access wisdom-related knowledge and examines the contribution of age and type of professional specialization to individual differences in wisdom-related knowledge. Women from 2 age groups/cohorts (young, M = 32 years; old, M = 71 years) and different professional specializations (human services vs. nonhuman services) were asked to think aloud about the life review of a fictitious woman who was either young or old. Verbal protocols were scored on 5 wisdom-related criteria: factual and procedural knowledge about life, life-span contextualism, relativism of values, recognition, and management of uncertainty. Three major findings emerged. First, human-services professionals outperformed the control group. Second, old adults performed as well as young adults. Third, for older adults wisdom-related performance was enhanced by the match between their own age and the age of the fictitious character.

Adaptation, Psychological↗

Glomerular mesangial cells and inflammatory macrophages ingest neutrophils undergoing apoptosis.

Apoptosis or programmed cell death of senescent neutrophils leading to their uptake by phagocytes is a general mechanism by which neutrophils may be removed from inflamed sites in vivo, promoting resolution rather than persistence of inflammation. We now report morphological evidence of neutrophil apoptosis leading to uptake by glomerular cells in rats with experimental glomerulonephritis. In addition to confirming that inflammatory macrophages take up apoptotic neutrophils, these studies indicated that glomerular mesangial cells can also participate in this mode of neutrophil clearance. Furthermore, human neutrophils which had been "aged" in vitro so as to undergo apoptosis were ingested by 31.5 +/- 1.3% (mean +/- SE) of cultured human mesangial cells, but there was minimal recognition of freshly isolated neutrophils (2.2 +/- 0.1%). Centrifugal elutriation of aged neutrophil populations yielded fractions with varying degrees of apoptosis (from 11.1 to 79.4%). Uptake of these fractions (by 8.2% to 59.8% of mesangial cells) was closely correlated with apoptosis (r = 0.96, P less than 0.0001). This demonstrated that recognition was dependent upon apoptosis, as in previous reports of macrophage recognition of aged neutrophils. However, by contrast, a partial requirement for serum was observed. These data indicate a hitherto unexpected function for the mesangial cell in clearance of senescent neutrophils from the glomerulus which may supplement inflammatory macrophage uptake of leucocytes undergoing apoptosis.

Animals↗

Sequence of the gene encoding the mitochondrial capsule selenoprotein of mouse sperm: identification of three in-phase TGA selenocysteine codons.

The mitochondrial selenoprotein is a major structural protein of the keratinous mitochondrial capsule in mammalian sperm, a structure that functions in shaping mitochondria into the helical sheath surrounding the flagellum. A cDNA clone (Kleene et al., 1990) was isolated previously encoding a protein whose predicted size and amino acid content of > 20% cysteine and proline closely resembled a selenoprotein in the bull mitochondrial capsule. The sequences of additional cDNAs and genomic DNA reported here reveal that the mouse mitochondrial capsule selenoprotein reading frame begins 54 codons further upstream than previously reported. Significantly, these 54 codons contain three in-phase UGA codons, which normally signify stop but encode selenocysteine in bacterial and mammalian selenoproteins. The coding region of the mitochondrial capsule selenoprotein gene is interrupted by a single intron. S1 mapping and primer extension demonstrate that the vast majority of MCS mRNAs are spliced using consensus 5' and 3' slice junctions in mammalian cells. However, two cDNAs have been identified that apparently represent rare mRNA variants produced by use of cryptic splice sites.

Amino Acid Sequence↗

Review of three decades of laboratory exercises in the preclinical curriculum at the Case Western Reserve University School of Medicine.

The authors reviewed the use of preclinical curricular time for laboratory exercises at the Case Western Reserve University School of Medicine from 1955-56 to 1988-89. Total hours decreased from over 1,000 in 1960-61 to just under 300 in 1988-89. From 1955-56 to 1985-86, laboratory hours devoted to animal and human physiology declined by 92%. Although the precise reasons for these changes--which have occurred in medical schools across the country--are difficult to document, the authors view them with concern. After considering the advantages and disadvantages of preclinical laboratory exercises, they conclude that the former still outweigh the latter. The further disappearance of laboratory exercises from the curriculum should be halted by efforts to revitalize them.

Curriculum↗

Autotransfusion of potentially culture-positive blood (CPB) in abdominal trauma: preliminary data from a prospective study.

Increased use of autotransfusion for traumatic hemorrhage may reduce amounts of banked blood needed for severe injuries. Autotransfusion is standard for traumatic hemothorax, but has been limited for abdominal injuries. This prospective study used microbiologic data from 152 patients with intestinal injuries. Where anticipated blood loss was greater than 1,000 mL, blood from the peritoneal cavity was cultured, washed, concentrated, and recultured before reinfusion. Infection rates were stratified using the Penetrating Abdominal Trauma Index (PATI). Fifty patients with PATI greater than 20 who received banked blood (group I) (mean: 1,800 mL) were compared with 20 patients (group II) who received autotransfused, potentially culture-positive blood (CPB) (mean: 3,900 mL). Wound infection rates were identical in both groups (25%). No statistically significant increase was found in site-specific infection risk when severity of injury was stratified according to PATI. Bacteremias, pulmonary infections, and urinary infections were not caused by bacteria cultured from autotransfused blood. We conclude that washed CPB may be autotransfused without significantly increased risk of infection in patients with severe abdominal injuries.

Abdominal Injuries↗

Identification of two novel human immunodeficiency virus type 1 splice acceptor sites in infected T cell lines.

The regulatory and accessory proteins of human immunodeficiency virus type 1 (HIV-1) are produced from singly or multiply spliced mRNAs. We have used HIV-1-specific oligonucleotide primer pairs in a polymerase chain reaction procedure on RNA from lymphocyte cell lines infected with HIV-1(228,200). The amplified products were analysed by hybridization with splice junction-specific oligonucleotide probes to determine splice donor/splice acceptor combination utilization, subcloned into a plasmid vector and the nucleotide sequences were obtained. Two novel splice acceptor sites have been identified.

Amino Acid Sequence↗

Radiation therapy of glottic carcinoma: Peter MacCallum Cancer Institute experience.

The medical records of patients with T1N0, T2N0 and T3N0 squamous cell carcinomas of the glottis treated at the Peter MacCallum Cancer Institute between January 1983 and October 1988 were retrospectively reviewed. One hundred and twenty-seven patients were identified. There were 93 T1, 26 T2 and eight T3 tumours. These patients were treated with curative radiotherapy (60-70 Gy). The survival from glottic cancer of patients with T1, T2 and T3 tumours at 5 years was estimated to be 97, 62 and 100% respectively. The local disease free survival for T1 and T2 disease at 5 years was estimated to be 82 and 65% respectively. The local disease free survival for T3 tumours at 2 years was estimated to be 63% with 5 year survival not yet reached. The surgical salvage rates for 24 radiotherapy failures were 77, 25 and 66% for T1, T2 and T3 tumours respectively. Radiotherapy remains the treatment of choice for T1 tumours and a viable alternative to primary laryngectomy in more advanced glottic tumours, with salvage surgery in reserve.

Age Factors↗

Hyperactivity and delay aversion--I. The effect of delay on choice.

Two experiments are reported in which hyperactive and control children repeatedly chose between small immediate and large delayed rewards. In experiment 1, the best choice option was manipulated by varying levels of delay after reward delivery. In experiment 2 it was manipulated by changing the economic constraint (10 minutes or 20 trials). Both groups were equally efficient at earning points under most conditions, but hyperactive children exhibited a maladaptive preference for the small reward under the trials constraint. The results suggest that hyperactive children were more concerned to reduce overall delay levels than either to maximize reward amount or immediacy.

Attention Deficit Disorder with Hyperactivity↗

Ethanol-associated alterations in the kinetics of putrescine uptake and metabolism by the regenerating liver.

Biosynthesis of the polyamines, putrescine, spermidine, and spermine is required for DNA synthesis and liver regeneration after partial hepatectomy. We have previously reported that chronic ethanol consumption impairs polyamine synthesis and significantly retards liver regeneration after partial hepatectomy. In those studies, supplementation with putrescine restored hepatic DNA synthesis in ethanol-fed rats but exerted no effect in pair-fed controls. These differences in the response to putrescine treatment may have resulted from ethanol-associated differences in hepatic uptake, release, or metabolism of putrescine. To resolve these issues and define more completely how putrescine treatment affects DNA synthesis, we now assess the kinetics of putrescine uptake and metabolism after intraperitoneal or intravenous injection of radiolabeled putrescine (1.2 mmol/kg, specific activity 1 microCi/mmol) into rats fed 36% ethanol diets or isocaloric, nonethanol diets for 6 weeks prior to partial hepatectomy. After putrescine treatment, hepatic putrescine concentrations were greater in ethanol-fed rats than controls. Differences in post-treatment hepatic putrescine levels between ethanol and pair-fed groups could not be explained by differences in the rates of hepatic putrescine uptake or excretion into bile; residual de novo synthesis of putrescine from ornithine or metabolism of hepatic putrescine to its polyamine products, spermidine and spermine. Indeed, supplemental putrescine was not appreciably converted to spermidine or spermine in either ethanol or control rats. Hence, these latter polyamines are unlikely to be responsible for the treatment-associated improvement in DNA synthesis that has been noted in ethanol-fed rats. This suggests that putrescine itself acts to restore hepatic DNA synthesis in ethanol-fed rats.

Alcoholism↗

Evaluation of the ability of primary selective enrichment to resuscitate heat-injured and freeze-injured Listeria monocytogenes cells.

Resuscitation rates of injured Listeria monocytogenes on conventional selective Listeria enrichment broth and nonselective Trypticase soy broth containing 0.6% yeast extract were compared. Cells were heated to 60 degrees C for 5 min or frozen at -20 degrees C for 7 days. Inoculation of Trypticase soy broth-yeast extract with the stressed cells resulted in growth that was superior to that in Listeria enrichment broth. Injured cells were fully recovered at 6 to 8 h.

Caseins↗

Analysis of a Caulobacter crescentus gene cluster involved in attachment of the holdfast to the cell.

Caulobacter crescentus firmly adheres to surfaces with a structure known as the holdfast, which is located at the flagellar pole of swarmer cells and at the stalk tip in stalked cells. A three-gene cluster (hfaAB and hfaC) is involved in attachment of the holdfast to the cell. Deletion and complementation analysis of the hfaAB locus revealed two genes in a single operon; both were required for holdfast attachment to the cell. Sequence analysis of the hfaAB locus showed two open reading frames with the potential to encode proteins of 15,000 and 26,000 Da, respectively. A protein migrating with an apparent size of 21 kDa in gel electrophoresis was encoded by the hfaA region when expressed in Escherichia coli under the control of the lac promoter, but no protein synthesis could be detected from the hfaB region. S1 nuclease analysis indicated that transcription of the hfaAB locus was initiated from a region containing a sequence nearly identical to the consensus for C. crescentus sigma 54-dependent promoters. In addition, a sequence with some similarity to ftr sequences (a consensus sequence associated with other Caulobacter sigma 54-dependent genes) was identified upstream of the hypothesized sigma 54 promoter. At least one of the hfaAB gene products was required for maximal transcription of hfaC. The sequence of hfaB showed some similarity to that of transcriptional activators of other bacteria. The C-terminal region of the putative gene product HfaA was found to be homologous to PapG and SmfG, which are adhesin molecules of enteropathogenic E. coli and Serratia marcescens, respectively. This information suggests that the protein encoded by the hfaA locus may have a direct role in the attachment of the holdfast to the cell, whereas hfaB may be involved in the positive regulation of hfaC.

Amino Acid Sequence↗

Initial level of care and clinical status in a managed mental health program.

Data from 9,055 adult intakes performed over two and a half years of a managed mental health care demonstration project in a large U.S. city were used as indirect measures of quality of care. The level of care to which patients were initially assigned was examined in relation to the patients' clinical status as judged by both managed care case managers and treatment providers. During the period, assignment to inpatient care of patients in almost every clinical category decreased. The decrease seemed to reflect a policy decision to limit use of all inpatient services rather than a selective elimination of unnecessary hospitalization. Case managers rated a smaller proportion of patients severely disturbed, partial hospitalization was rarely used as an alternative to inpatient care, and detoxification services were increasingly used as an inpatient alternative. Although these data reinforce common beliefs about managed care, the quality of managed care programs can be accurately assessed only with data collected specifically for evaluation purposes.

Alcoholism↗

Specific and non-specific effects of educational intervention for families living with schizophrenia. A comparison of three methods.

Three methods of delivering an educational intervention to families living with a schizophrenic relative were compared in terms of their efficacy in improving understanding and promoting family and patient well-being. Relatives receiving education in a group acquired more information than relatives receiving information by post or on video, but these differences were not maintained at six-month follow-up. The inclusion of homework assignments did not significantly affect gains in knowledge or any of the non-specific effects observed. The intervention overall led to considerable gains in knowledge, increased optimism concerning the family's role in treatment, and reductions in relatives' stress, which were maintained at follow-up. Fear was reduced in the short-term. Significant improvements in social function were observed at follow-up. The results suggest that the delivery of information, rather than the mode of delivery, is the crucial element in the intervention; however, the additional contextual factors operating in a group may be important if the full potential of education is to be realised.

Adult↗