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Biomedical subjects

S White

Publications and source records attributed to S White.

At least 181 records · Page 10Linked to original sources
PubMed1993

Infections due to antibiotic-resistant gram-positive cocci.

Gram-positive cocci are becoming increasingly resistant to traditionally used antimicrobial agents. Staphylococcus aureus, coagulase-negative staphylococci, the enterococcus, and Streptococcus pneumoniae are the most commonly encountered of such pathogens in clinical practice. Clinicians should be keenly aware of the usual types of infections that are caused by these organisms and the importance of documenting susceptibilities of infecting strains. The basic mechanisms of resistance should be familiar to clinicians so that an inappropriate empiric regimen will not be selected (e.g., addition of a beta-lactamase inhibitor for penicillin-resistant pneumococci). Vancomycin remains the agent of choice, sometimes in combination with gentamicin and/or rifampin, for most cases of infection due to these resistant gram-positive organisms. Last, increased efforts toward prevention, such as strict adherence to infection control measures, selective use of broad-spectrum antibiotics, and increased use of pneumococcal vaccine, may be useful to help stem the rising tide of infections due to resistant gram-positive cocci.

Anti-Bacterial Agents↗
PubMed1993

Pharmacokinetics of ampicillin and sulbactam in pregnancy.

OBJECTIVE: This study evaluated the effects pregnancy had on pharmacokinetic parameters of ampicillin and sulbactam. STUDY DESIGN: Twenty-two women undergoing cesarean section for obstetric indications were randomly assigned to receive a single intraoperative dose of either 1 gm of ampicillin intravenously or 1 gm of ampicillin plus 0.5 gm of sulbactam intravenously after umbilical cord clamping. Blood was drawn from an indwelling intravenous catheter at 15, 30, 45, 60, 120, 240, and 360 minutes after infusion of the antibiotic for determination of serum ampicillin and/or sulbactam levels. Pharmacokinetic parameters were determined by fitting data (serum concentrations versus time) to a single-compartment model that provided elimination rate constants, beta-intercept (calculated concentration at 0 minutes), area under the time-versus-concentration curve, half-life of the drug, total body clearance, and volume of distribution. After the examination 6 weeks post partum, each subject was given an additional dose of the drug she had received during cesarean section, and a second pharmacokinetic study was performed and compared with the previous results. RESULTS: Pregnancy significantly increased the elimination rate constant, decreased the area under the drug-versus-time curve, shortened the serum half-life, and increased the total body clearance in comparison with these parameters in the nonpregnant state for ampicillin. Sulbactam kinetics were similarly affected, although these changes failed to attain statistical significance. CONCLUSION: Because pregnancy is associated with more rapid elimination of beta-lactam drugs, physicians treating infections in pregnant or newly parturient women should consider using shorter intervals between antibiotic doses when a range of dosage intervals is under consideration.

Ampicillin↗
PubMed1993

Pediatric psychologists' perceptions of their work settings.

Describes the results of a survey of pediatric psychologists' perceptions of their work settings. Respondents (n = 261) described heterogeneous work settings, professional activities, expectations for workload and administrative arrangements. Clinical activities were prominent, accounting for nearly half the respondents' time. Respondents generally reported high levels of overall satisfaction with their work environments. Highest ranked sources of satisfaction included professional autonomy, patient care, and relationships with colleagues. Highest ranked sources of dissatisfaction included lack of time for research, salary, and patient care workload. Pediatric psychologists in private practice reported higher work satisfaction than those in other settings. Findings have implications for the work-related functioning of pediatric psychologists that should be addressed in research and professional activity.

Adult↗
PubMed1993

Identification of a novel smooth muscle myosin heavy chain cDNA: isoform diversity in the S1 head region.

Smooth muscle myosin heavy chain (SMHC) isoforms, SM1 and SM2, are the products of alternative splicing from a single gene (P. Babij and M. Periasamy. J. Mol. Biol. 210: 673-679, 1989). We have previously shown that this splicing occurs at the 3'-end of the mRNA, resulting in proteins that differ at the carboxyterminal (R. Nagai, M. Kuro-o, P. Babij, and M. Periasamy. J. Biol. Chem. 264: 9734-9737, 1989). In the present study we demonstrate that additional SMHC isoform diversity occurs in the globular head region by isolating and characterizing two distinct rat SMHC cDNA (SMHC-11 = SM1B and SMHC-5 = SM1A). Sequence comparison of the two clones reveals that they are completely identical in their coding regions, except at the region encoding the 25/50 kDa junction of the myosin head, where the SM1B isoform contains an additional seven amino acids. This divergent region is located adjacent to the Mg(2+)-ATPase site, and differences in this region may be of functional importance. Ribonuclease protection analysis demonstrates that the corresponding SM1B and SM1A mRNA messages are coexpressed in all smooth muscle tissues; however, the proportion of the two mRNA present differs significantly between tissues. The SM1A-type mRNA predominates in most smooth muscle tissues, with the exception of intestine and urinary bladder, which contain greater proportions of the SM1B message. The differential distribution of these two isoforms may provide important clues toward understanding differences in smooth muscle contractile properties.

Alternative Splicing↗
PubMed1993

Control of resting bronchial hemodynamics in the awake dog.

In the resting awake dog a continuous-wave Doppler flow transducer on the right bronchoesophageal artery inscribes a sharp early systolic spike and low flow in late systole and throughout diastole, indicating a highly resistive bed. An analysis of autonomic factors using intravenous, cumulative, and randomly applied cholinoceptor, beta 1- and beta 2-adrenoceptor, and alpha 1- and alpha 2-adrenoceptor antagonists indicates that the low vascular conductance is due to cholinoceptor and alpha 1- and alpha 2-adrenoceptor effects in a ratio 3.6:1. No beta-adrenoceptor tone is present. Sighing behavior invokes a transient (< 2 s) fall in intrapleural pressure (and thus rise in bronchovascular transmural pressure) of 10-30 mmHg, which is followed by a two- to threefold increase over 30 s in bronchial flow and conductance, an effect simulated in 50% of dogs when bronchovascular transmural pressure is acutely raised and maintained over 40-60 s by inflating an intra-aortic balloon distal to the origin of the bronchial artery. Autonomic blockade has no effect on bronchovascular dilatation evoked either by sighing or by balloon inflation. It is concluded that, in the resting bronchial circulation, there exists strong cholinoceptor and alpha-adrenoceptor-based vasoconstrictor activity which can be overpowered by strong nonadrenergic noncholinergic local vasodilator reflexes evoked by sudden changes in intrathoracic transmural pressure possibly acting on stretch-sensitive sensory nerve endings containing substance P, calcitonin gene-related peptide, and neurokinins. The tonic vasoconstrictor but not the sigh-evoked vasodilator effects are sensitive to pentobarbital sodium anesthesia.

Animals↗
PubMed1993

Smooth muscle myosin regulation by serum and cell density in cultured rat lung connective tissue cells.

RNA and protein analyses were used to detect expression of SM1 and SM2 smooth muscle myosin heavy chain (MHC) in cultured adult rat lung connective tissue cells (RL-90). Smooth muscle MHC mRNA expression in confluent cells grown in 10% serum was approximately 50% of the level in adult stomach. Similar results were obtained in cells cultured at low density (25% confluency) in 1% serum. However, in low-density cultures transferred to 10% serum for 24 h, the level of MHC mRNA decreased to approximately 20% of that in adult stomach. Smooth muscle alpha-actin showed a pattern of expression similar to that for smooth muscle MHC. Expression of nonmuscle MHC-A mRNA was higher in all culture conditions compared to stomach. MHC-A mRNA expression was less in low-density cultures in low serum and increased when low-density cultures were transferred to 10% serum for 24 h. MHC-B mRNA expression was less in low- vs. high-density cultures. In contrast to MHC-A, however, MHC-B mRNA expression in low-density cultures was higher in low serum. Immunofluorescence and immunoblotting with SM1-specific antibody demonstrated the presence of the SM1 protein isoform as well as reactivity to a protein band migrating slightly faster than SM2. These results demonstrate that cultured rat lung connective tissue cells express smooth muscle MHC and that expression is modulated by culture conditions.

Amino Acid Sequence↗
PubMed1993

Myosin isoform expression in developing and remodeling rat lung.

The tissue distribution of myosin isoforms was examined in developing smooth muscle of rat lung. Antisera employed included a general smooth muscle myosin antibody (aSMMG) and two smooth muscle myosin isoform specific antisera (aSM1 and aSM2). In the pseudoglandular, canalicular, and saccular lung, the isoform-specific aSM1 antiserum was very lightly reactive only with large airway and not reactive with vascular smooth muscle, whereas aSM2 was unreactive with any lung cells. During these same stages, the aSMMG serum reacted well with the mesenchymal coat around the larger airways, declining in intensity as the tube size diminished. Vascular smooth muscle elements had only moderate reactivity at this time. In the adult, aSM1 marked airway smooth muscle as well as the tips of the alveolar septae. Vascular reactivity was seen in both arterial and venous elements. An identical distribution of reactivity was seen for aSMMG. aSM2 reactivity appeared confined primarily to airway smooth muscle and was absent from all but the largest vascular structures. Companion Western blot analyses confirmed the presence of SM1 in fetal and mature tissues as well as the relative lack of SM2 in all but the fully differentiated airways. Lung injury due to intratracheal instillation of bleomycin is characterized by a proliferation of mesenchymal cells similar to immature smooth muscle cells. These cells express smooth muscle forms of actin but lacked the mature smooth muscle myosin isoforms. In summary, differentiation of smooth muscle in the lung proceeds with progressive replacement of nonmuscle isoforms of myosin with differentiation-specific forms. In this regard, the maturation of vascular muscle tissue lags behind that of nonvascular (visceral) muscle structures.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

An end to D-I-Y cremation?

This article examines whether to be lawful a cremation must be carried out in accordance with the Cremation Acts. It argues that it need not be but points out that any lacuna in the Acts will be plugged if and when the new consolidated Cremation Regulations are passed. It then considers the implication of this reform for the disposal of babies born dead before the legal age of viability.

History, 19th Century↗
PubMed1993

Hepatocellular proliferation in ibuprofen-treated mice.

Female B6C3F1 mice were treated with ibuprofen for 2 wk or 90 days to monitor effects on hepatocellular proliferation during acute and subchronic exposure. Proliferation was assessed by bromodeoxyuridine labeling. Mice treated with 100, 200, or 400 mg/kg ibuprofen for 2 wk had significantly increased liver weights. A dose-related increase in the number of labeled hepatocytes per 1,000 hepatocytes suggested that the weight increases were in part a result of hepatocellular proliferation. Hepatocellular hypertrophy also contributed to the increased liver size as indicated by decreases in the number of hepatocytes per high power field. Ultrastructural evaluation indicated that hepatocyte peroxisome size increased significantly in treated mice. Mice treated with 100 or 200 mg/kg ibuprofen for 90 days and given bromodeoxyuridine during the last 2 wk of ibuprofen exposure had statistically significant increases in relative liver weights. However, the number of labeled hepatocytes per 1,000 hepatocytes was not increased, and there was no evidence of hepatocellular hypertrophy. Mice given 200 mg/kg ibuprofen for 90 days had significantly decreased serum triglycerides. These findings indicate that ibuprofen treatment of mice results in hepatomegaly characterized by hepatocellular hypertrophy and hyperplasia. Peroxisomal changes may be contributory to the pathogenesis of this lesion.

Animals↗
PubMed1993

Laparoscopic colostomy closure.

Perforated sigmoid diverticulitis often results in the patient undergoing a sigmoid resection, closure of the rectal stump, and an end sigmoid colostomy. To reestablish intestinal continuity, the patient must undergo a second major intra-abdominal operation. We have developed a technique of laparoscopic colostomy closure to reestablish intestinal continuity and have used it in two patients. Because of the reduced operative pain and shorter recovery period, this minimally invasive technique would be a better surgical alternative to colostomy closure.

Aged↗
PubMed1993

Do elderly patients mind how doctors address them?

A survey was carried out in the Geriatric Unit at Cork Regional Hospital to determine how elderly patients would like to be addressed by their doctor. Two hundred patients over the age of 65 were given a Questionnaire asking them to state their preference. Only a minority (4.5%) expressed a definite preference for the formal mode of address. The remainder either did not mind (38%) or preferred to be addressed by their first name (57.5%). We concluded that most elderly patients do have a preference and this should be established on admission.

Aged↗
PubMed1993

Stabilised p53 facilitates aneuploid clonal divergence in colorectal cancer.

Mutations in the p53 tumour suppressor gene are amongst the most frequent genetic abnormalities acquired in tumours. Recent studies in vitro suggest that mutant p53 destabilises the genome and facilitates development of aneuploidy. Here, in a study of 83 colorectal carcinomas, we demonstrate that alterations in p53 (detected by immunocytochemical stabilisation) precede and apparently facilitate divergence of aneuploid sub-clones. Aneuploidy in these tumours (but not those with normal p53) is predominantly in the subtetraploid range, suggesting that endoreduplication is important in its origin. This association with a specific phase of carcinoma progression is not shared by other commonly acquired genetic abnormalities in these tumours. These observations highlight the critical role of p53 in the regulation of abnormal chromosome replication and afford an explanation for the association between p53 abnormalities, aneuploidy and biological aggression in cancer.

Adenoma↗
PubMed1993

Microbial carriage, sepsis, infection and acute GVHD in the first 25 BMT at the Royal Liverpool Children's Hospital.

The first 25 BMTs at the Royal Liverpool Children's Hospital (Alder Hey) were performed between April 1987 and July 1991. The aim of this report is to evaluate selective decontamination of the digestive tract (SDD) during the first post-BMT month in this series of 14 allografts and 11 autografts. SDD is a method used to abolish carriage of potentially pathogenic microorganisms including yeasts, Staphylococcus aureus and Gram-negative bacilli (GNB). Chlorhexidine mouth wash was used to decontaminate the oropharynx, and neomycin, colistin (polymyxin E) and nystatin (NEOCON) were given to eradicate gut carriage. Oropharyngeal decontamination was successful in 48% of patients, gut carriage was abolished in 60%, and eradication of the carrier state at both sites was achieved in 33%. A septic response was seen in 76% of children and 36% developed septicaemia (indigenous Gram-positive cocci only). A low carriage index for the target microorganisms during the study manoeuvre of SDD was associated with negative blood cultures (p < 0.01). Acute GVHD occurred in 28% of allografts, but was seen in none of the successfully decontaminated children (p < 0.05). It is concluded that septicaemia from yeasts and GNB, but not the septic response, were successfully prevented by SDD.

Adolescent↗