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Biomedical subjects

J R Smith

Publications and source records attributed to J R Smith.

At least 127 records · Page 7Linked to original sources
PubMed1998

Peripherally inserted central catheters revisited.

BACKGROUND: This study compares central venous catheters (CVC) and peripherally inserted central catheters (PICC) for indications for insertion, complications, and economic impact. METHODS: A retrospective review of 838 (283 CVC, 555 PICC) consecutively placed venous catheters reflected 49,365 CVC and 11,814 PICC days. RESULTS: There were 57 (20%) complications in the CVC group, 197 (35%) complications in the PICC group. PICC were associated with a statistically significant increase in the incidence of catheter malfunction (P = 0.0005), arm vein phlebitis (P = 0.0004), and overall complications (P = 0.00001). A higher complication rate was noted in PICC inserted for chemotherapy (P = 0.00001) and parenteral hyperalimentation administration (P = 0.04). Charges for inpatient insertion of PICC and CVC were $500 and $2,500, respectively. CONCLUSIONS: PICC have a significantly higher complication rate than CVC. PICC provide cost-effective central access of 2 to 3 weeks' duration, reserving operatively placed CVC for longer access requirements.

Adult↗
PubMed1998

Serotonin and vasoconstrictor synergism.

Contractile synergism between serotonin (5-hydroxytryptamine, 5-HT) and other vasoconstrictor substances has been observed in a number of peripheral and cerebrovascular blood vessels. This phenomenon may play an important role in certain pathological states such as hypertension, peripheral vascular disease, and coronary spasm. In the present review, we summarize studies on the synergism between serotonin and other vasoconstrictor agents and focus on a recently described type of vasoconstrictor synergism in which precontraction with a non-5-HT receptor agonist yields an enhanced contractile response to serotonin which is mediated by previously inactive or "silent" 5-HT receptor subtypes.

Animals↗
PubMed1998

Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001.

A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

Carbonates↗
PubMed1998

Basic pathogenic mechanisms operating in experimental models of acute anterior uveitis.

Acute anterior uveitis is a recurrent inflammatory disease of the eye that occurs commonly, is distressing for the patient, and may have potentially blinding sequelae. The pathogenesis of the disease is poorly understood, and anti-inflammatory treatment is consequently non-specific and may be associated with significant complications. Animal models are a possible key to a better understanding of this disease. In one model, rats and mice develop a relatively short-lived anterior uveal inflammation almost immediately after systemic injection of bacterial endotoxin. Accumulating evidence suggests that cytokine production by resident uveal macrophages initiates endotoxin-induced uveitis which is characterized by an infiltration of neutrophils and mononuclear cells. A second model displays features in keeping with a delayed-type hypersensitivity immune response. Experimental melanin-induced uveitis is an acute recurrent uveitis with delayed onset but extended duration, observed when rats are immunized with bovine ocular melanin. Both animal models have clinical features in common with acute anterior uveitis, although experimental melanin-induced uveitis appears to mimic the human disease more closely. Novel treatment options to target implicated inflammatory cells and molecules are currently under consideration.

Acute Disease↗
PubMed1998

Bacterial vaginosis and cervical intraepithelial neoplasia--cause or coincidence?

Evidence regarding a causal relationship between bacterial vaginosis and cervical intraepithelial neoplasia has so far been incomplete and conflicting. To determine whether bacterial vaginosis is associated with cervical intraepithelial neoplasia a retrospective study was conducted at the Genitourinary Medicine Clinic at Southlands Hospital, Shoreham-by-Sea, UK. Three hundred patients who presented to the clinic with a first diagnosis of genital warts in the absence of other sexually transmitted diseases were recruited. Results of cervical cytology and where abnormal, histology on colposcopically directed punch biopsies were collected. Bacterial vaginosis was diagnosed by the detection of clue cells on Gram-staining of a high vaginal swab, positive amine test, vaginal pH above 4.5 and the presence of characteristic vaginal discharge. Odds ratio showed an increased prevalence of cervical intraepithelial neoplasia associated with bacterial vaginosis. The results suggest that a prospective cross sectional study should be performed to formally test the hypothesis that bacterial vaginosis predisposes to cervical intraepithelial neoplasia.

Journal Article↗
PubMed1998

Blunt-tipped versus sharp-tipped needles: wound morbidity.

Blunt-tipped needles have previously been shown to reduce needle-stick injury but the issue of morbidity had not been addressed. As awareness of the need for universal precautions heightens, concerns have been raised about any possible morbidity brought about by their use. We present the results of a randomised, controlled study which investigated wound morbidity following caesarean section. Of the 204 women randomised to closure with sharp or blunt-tipped needles, none developed anything other than superficial infection and there were no significant differences between the two groups. We conclude that the use of blunt-tipped needles does not cause an increase in wound morbidity.

Clinical Trial↗
PubMed1998

Diagnosing the systemic associations of anterior uveitis.

Up to one-half of patients with anterior uveitis suffer from related systemic diseases. The common associations are the seronegative arthropathies and, in children, juvenile chronic arthritis. Anterior uveitis may also occur in the context of sarcoidosis or Behçet's disease. Syphilis and tuberculosis remain a significant problem for specific populations and may be the cause of anterior uveitis in these groups. By thorough clinical history and the correct selection and interpretation of simple investigations, it is generally possible for the ophthalmologist to make or exclude a systemic diagnosis, predict the ocular prognosis and direct selected patients to the appropriate physician. Diseases that threaten the patient's wellbeing must certainly be recognized. In the present review we present a method for identifying the systemic associations of anterior uveitis.

Adolescent↗
PubMed1998

Uveal mast cells are not required for rodent uveitis.

Uveal mast cells have previously been considered to be vital mediators of experimental uveitis. We extended the study of these cells to experimental melanin-induced uveitis (EMIU), a recently described clinically relevant model, and re-examined their role in endotoxin-induced uveitis (EIU) using genetically mast cell-depleted mice on a single background. EMIU was induced in Fischer 344 rats by immunisation with bovine ocular melanin (250 microgram. Animals were killed immediately, and on days 1 and 3 of clinical disease. Numbers of uveal mast cells and the percentage of degranulated cells were counted in whole-mount preparations. There was no significant change in either measure across the selected time points. To induce EIU, normal and mast cell-depleted DBA/2 mice were injected with Escherichia coli lipopolysaccharide (400 microgram). Cells infiltrating the eye 24 h after injection were quantified in 5 micrometer ocular cross-sections. Disease was not significantly reduced in the mast cell-depleted mutants. We conclude that uveal mast cells are not required for the development of EMIU or, in contrast to earlier work, EIU.

Animals↗
PubMed1998

Clinical and physiological effects of stereotaxic bilateral amygdalotomy for intractable aggression.

The amygdala is thought to be an important neural structure underlying the "fight-or-flight" response, but information on its role in humans is scarce. The clinical and psychophysiological effects of amygdalar destruction were studied in 2 patients who underwent bilateral amygdalotomy for intractable aggression. After surgery, both patients showed a reduction in autonomic arousal levels to stressful stimuli and in the number of aggressive outbursts, although both patients continued to have difficulty controlling aggression. The "taming effect" reported after bilateral amygdalar destruction may be due to the amygdala's inadequate processing of perceived threat stimuli that would normally produce a fight-or-flight response.

Adult↗
PubMed1998

Mice deficient in tumor necrosis factor receptors p55 and p75, interleukin-4, or inducible nitric oxide synthase are susceptible to endotoxin-induced uveitis.

PURPOSE: To investigate the roles of tumor necrosis factor-alpha (TNF-alpha), interleukin-4 (IL-4), and inducible nitric oxide synthase (iNOS) in endotoxin-induced uveitis (EIU) using gene knock-out mice. METHODS: Mice (C57BL/6 x 129) either of normal phenotype or deficient in the genes encoding one or both tumor necrosis factor receptors (TNFR p55 and TNFR p75), IL-4, or iNOS were given footpad injections of 400 micrograms Escherichia coli lipopolysaccharide. Animals were killed 24 hours later, and infiltrating cells were counted on 5-micron ocular cross-sections through the optic nerve. RESULTS: All abnormal mouse phenotypes were susceptible to EIU. Yet, TNFR p55 and IL-4 gene knock-out mice experienced less ocular inflammation than control animals (P = 0.021 and 0.007, respectively), whereas disease was not reduced for iNOS-deficient mice. Mice deficient in TNFR p55 and TNFR p75 experienced milder EIU than mice lacking TNFR p75 alone (P = 0.046). CONCLUSIONS: Mice deficient in TNFR p55 and TNFR p75, IL-4, or iNOS retain the susceptibility to EIU, but TNF-alpha and IL-4 influence the influx of inflammatory cells to the eye during this disease.

Acute Disease↗
PubMed1998

The impact of child support on cognitive outcomes of young children.

We use the National Longitudinal Survey of Youth-Child data to address three questions. First, does the receipt of child support have beneficial effects for children with absent fathers apart from increasing income? Second, do the effects of child support differ when child-support awards and payments are made cooperatively as opposed to being court ordered? Third, are any positive effects of child support solely a product of unmeasured differences among fathers and families? Controlling for the socioeconomic characteristics of the child and family, we find some evidence that receipt of child support has a positive impact on children's cognitive test scores over and above its contribution to total income. However, the effects vary by test, by race, and by reason for father's absence. Our results also indicate that the distinction between cooperative and noncooperative awards is important. Finally, our instrumental variables estimates show that the effects of child support persist after we control for unobserved characteristics of fathers and families.

Achievement↗
PubMed1998

A quantitative method for analysing AFM images of the outer surfaces of human hair.

Cuticle step height is an important parameter for the quantitative assessment of human hair. This paper describes a novel, computational method for the rapid calculation of step heights from atomic force microscope images obtained from large numbers of specimens. Such an approach is necessary to allow a statistical analysis of the inherently wide distribution of cuticle step heights characteristic of a single hair sample. The method described will be of use to cosmetic formulation chemists and forensic scientists and also to dermatologists in the field of disease diagnosis.

Analysis of Variance↗
PubMed1997

Early age at diagnosis in families providing evidence of linkage to the hereditary prostate cancer locus (HPC1) on chromosome 1.

In a recent study of 91 families having at least three first degree relatives with prostate cancer, we reported the localization of a major susceptibility locus for prostate cancer (HPC1) to chromosome 1 [band q24; J. R. Smith et al., Science (Washington DC), 274: 1371-1373, 1996]. There was significant evidence for locus heterogeneity, with an estimate of 34% of the families being linked to this locus. In this report, we investigate the importance of age at diagnosis of prostate cancer and number of affected individuals within a family as variables in the linkage analysis of an expanded set of markers on 1q24. Under two different models for the prostate cancer locus, we find that the evidence for linkage to HPC1 is provided primarily by large (five or more members affected) families with an early average age at diagnosis. Specifically, for 40 North American families with an average age at diagnosis <65 years, the multipoint lod score is 3.96, whereas for 39 families with an older average age at diagnosis, this value is -0.84. Assuming heterogeneity, the proportion of families linked is 66% for the 14 families with the earliest average ages at diagnoses, but it decreases to 7% for the families with the latest ages at diagnoses. A similar age effect is observed in 12 Swedish pedigrees analyzed. To test the hypotheses generated by these analyses, we examined an additional group of 13 newly identified prostate cancer families. Overall, these families provided additional evidence for linkage to this region (nonparametric linkage Z = 1.91; P = 0.04 at marker D1S1660), contributed primarily by the families in this group with early age at diagnosis [nonparametric linkage Z = 2.50 (P = 0.01) at D1S422]. These results are consistent with the existence of a locus in this region that predisposes men to develop early-onset prostate cancer.

Age Factors↗
PubMed1997

Characteristics of prostate cancer in families potentially linked to the hereditary prostate cancer 1 (HPC1) locus.

CONTEXT: Approximately 9% of prostate cancer cases have been estimated to result from inheritance of mutated prostate cancer susceptibility genes. Few data exist as to whether there are clinical differences between prostate cancers that are inherited and those that occur in the general population. OBJECTIVE: To investigate phenotypic characteristics of families potentially linked to the hereditary prostate cancer 1 (HPC1) locus on chromosome 1q24-25. DESIGN: Retrospective case study in which clinical data were extracted from medical and pathological records. FAMILIES: A total of 74 North American families with hereditary prostate cancer. Prostate cancer cases from the National Cancer Data Base were used as a reference population for comparison. MAIN OUTCOME MEASURES: The families were divided into 2 groups: either potentially linked (33 families with 133 men with prostate cancer), and thus likely to be carrying an altered HPC1 gene, or potentially unlinked (41 families with 172 men with prostate cancer), on the basis of haplotype analysis in the region of HPC1. The age at diagnosis of prostate cancer, serum prostate-specific antigen levels, digital rectal examination status, stage, grade, primary treatment of prostate cancers, and occurrence of other cancers were compared between the groups. RESULTS: The mean age at diagnosis of prostate cancer for men in potentially linked families was significantly lower than for men in potentially unlinked families (63.7 vs 65.9 years, respectively, P=.01; mean age at diagnosis in the reference population was 71.6 years). Higher-grade cancers (grade 3) were more common in potentially linked families, and advanced-stage disease was found in 41% of the case patients in potentially linked families compared with 31% in both the potentially unlinked families and the reference groups (P=.03 for the latter comparison). In the other clinical parameters, we found no significant differences between the groups. A modest excess of breast cancer and colon cancer was found in potentially linked families in comparison with potentially unlinked families, but this difference was not statistically significant. CONCLUSIONS: Families that provide evidence for segregation of an altered HPC1 gene are characterized by multiple cases of prostate cancer that, in most respects, are indistinguishable from nonhereditary cases. However, 3 characteristics were observed: younger age at diagnosis, higher-grade tumors, and more advanced-stage disease. Our study shows that a significant fraction of hereditary prostate cancers are diagnosed in advanced stages, emphasizing the clinical importance of early detection in men potentially carrying prostate cancer susceptibility genes. These findings support the current recommendations to screen men with a positive family history of prostate cancer beginning at age 40 years.

Age Factors↗