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Biomedical subjects

M S Smith

Publications and source records attributed to M S Smith.

At least 109 records · Page 6Linked to original sources
PubMed1995

Comprehensive evaluation and treatment of recurrent pediatric headache.

Continuity of care with a clinician who has established a therapeutic alliance is the most important aspect of recurrent pediatric headache management. The provider should assume a concerned and supportive manner that promotes self-esteem and self-mastery and control. Patient and family efforts to reduce functional disability and return to normal activities should be strongly reinforced. Treatment regimens should be reviewed for side effects, compliance, and perceived efficacy. Behavioral techniques should be reviewed in detail with opportunities for the clinician to "trouble shoot" any difficulties encountered by the patient. Periods of potentially increased stress (eg, transitions or loss) should be anticipated and managed prospectively. The clinician should periodically reassess possible psychosocial issues and make appropriate mental health referrals. In the long run, regular follow-up by the primary care clinician remains the most important factor in the successful management of recurrent pediatric headache.

Adolescent↗
PubMed1995

Detection of herpesvirus DNA in cottontop tamarins: no association with colitis.

Colitis occurs spontaneously in the cottontop tamarin; it shares similar clinical, endoscopic and histological features with, and has a similar response to treatment as, human ulcerative colitis. An association between human ulcerative colitis and the presence of DNA from multiple herpesviruses (human herpesvirus 6 (HHV-6), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in the colon has been described. Intestinal herpesvirus infection may be involved in the pathogenesis of this condition. In a pilot study, coded full thickness colonic specimens from 27 cottontop tamarins were examined for the presence of HHV-6, CMV and EBV DNA using the nested polymerase chain reaction. The sections represented a spectrum of disease activity ranging from histologically normal bowel to severe colitis. A low prevalence of DNA from these viruses was found, which bore no relation to the presence of inflammation. Although these herpesviruses may have a pathogenetic role in human ulcerative colitis, they are not associated with colitis in this animal model.

Animals↗
PubMed1995

The specific contribution of the novel alpha-1D adrenoceptor to the contraction of vascular smooth muscle.

With a selective antagonist, the specific contribution of the alpha-1D adrenoceptor (AR) to vascular smooth muscle contraction has been assessed. BMY 7378 bound to membranes expressing the cloned rat alpha-1D AR with a > 100-fold higher affinity (K1 = 2 nM) than binding to either the cloned rat alpha-1A AR (Ki = 800 nM) or the hamster alpha-1B AR (Ki = 600 nM). BMY 7378 exhibited differential potency in inhibiting vascular smooth muscle contraction. In the rat aorta and iliac artery, BMY 7378 was a high-affinity antagonist, producing parallel shifts in the phenylephrine concentration-response curve. The dissociation constants for this compound by Schild analysis were 0.95 and 4 nM for the aorta and iliac artery, respectively. The slopes of these Schild plots were not significantly different from unity. BMY 7378 was a weak antagonist in the rat caudal, mesenteric resistance and renal arteries, with Schild slopes significantly < 1. With ribonuclease protection assays, alpha-1D mRNA was found in all blood vessels examined. These data suggest that (1) BMY 7378 is a selective alpha-1D AR antagonist that can be used in functional systems to assess the contribution of this receptor in vascular smooth muscle contraction; (2) the alpha-1D AR appears to play a major role in the contraction of the aorta and iliac artery; (3) despite the fact that the mRNA for the alpha-1D AR can be detected in the caudal, mesenteric resistance (4) and renal arteries, it does not appear to play a role in mediating contraction of these blood vessels; and (4) expression of alpha-1D mRNA in a particular artery does not ensure that this receptor is involved in regulating the contraction of that artery.

Animals↗
PubMed1995

Prolactin receptor expression by rat NK cells.

We have recently begun investigating the effects of prolactin (PRL) on the function, or growth and differentiation of rat NK cells. Initially, we sought to determine the expression of a receptor for PRL (PRLr) on rat NK cells and to determine the effects of interleukin 2 (IL-2) on its expression. By a combination of reverse transcription/polymerase chain reaction (RT/PCR) and Southern blotting, we were able to identify a PRLr specific transcript using RNA isolated from highly purified, IL-2-activated NK (A-NK) cells. Using primers specific for unique portions of the major forms of PRLr transcripts in liver and ovary, it was determined that the NK cell PRLr has some homology with the major form of transcript for PRLr found in rat liver. By flow cytometric and 251-PRL binding analyses, we determined that A-NK cells expressed detectable levels of PRLr internally. Surface PRLr was not detectable by flow cytometry on freshly isolated NK cells from normal rats, and incubation of NK cells with rIL-2 did not induce detectable surface PRLr. Similarly, incubation of NK cells with PRL was not found to induce expression of the alpha chain of the IL-2 receptor (IL-2ra; CD25) on NK cells or other lymphoid cells. However, we were able to detect surface expression of PRLr on NK cells from bromocriptine-treated rats. Taken together, these data indicate that both cultured and freshly isolated populations of NK cell express PRLr.

Animals↗
PubMed1994

Use of Fos-related antigens (FRAs) as markers of neuronal activity: FRA changes in dopamine neurons during proestrus, pregnancy and lactation.

This manuscript describes the use of staining of Fos-related antigens (FRAs) as markers for changes in neuronal activity. The model system consisted of the tuberoinfundibular dopamine (TIDA) neurons located in the arcuate nucleus of the hypothalamus. Under normal conditions, these neurons are devoid of c-Fos staining even though the neurons are tonically active and can express FRAs. During specific neuroendocrine states the neurons undergo changes in activity, as described by other studies. At times when the activity is relatively high as in pregnancy and during proestrus, approximately 50%-60% of the TIDA neurons expressed FRA immunoreactivity. Moreover changes over the course of proestrus paralleled known shifts in TIDA activity (declining as the day progressed). At times when TIDA activity is suppressed, such as during lactation, FRA staining in TIDA neurons was markedly reduced or absent. Upon removal of the suckling stimulus, FRA staining rose to reach peak expression 12-24 h after pup removal (without coordinate induction of c-Fos). These data suggest that FRA staining can serve as a useful marker of activity in the TIDA neurons which permits not only assessment of stimulated activity but also suppressed function in the neurons. A cautionary note in using this approach along with acquisition of serial blood samples for hormone measurement is that surgical procedures for monitoring plasma hormone levels are associated with strong long-lived induction of FRAs (and c-Fos) in many neurons (including the TIDA neurons) that can confound interpretation of FRA staining.

Analysis of Variance↗
PubMed1994

Lactation-induced deficits in NMDA receptor-mediated cortical and hippocampal activation: changes in NMDA receptor gene expression and brainstem activation.

During lactation, there is an inhibition of cortical and hippocampal activation in response to N-methyl-D,L-aspartate (NMA), but not kainate, as assessed by induction of c-Fos expression. To study whether changes in NMDA receptor function may account for this inhibition, NMDA receptor subunit (NMDAR1) mRNA levels were measured by both Northern analysis and in situ hybridization. Analysis of NMDAR1 gene expression by Northern blot analysis did not reveal significant differences between cycling and lactating rats. Using in situ hybridization, NMDAR1 mRNA levels in several cortical and hippocampal areas appeared to be smaller in lactating rats, compared to cycling rats, although these differences reached significance only in the fronto-parietal cortex and piriform cortex. These subtle changes in NMDAR1 receptor subunit gene expression during lactation are not likely to account for the global lack of neuronal activation in response to NMA. However, it is possible that there may be changes in other NMDA receptor subunits that could account for the deficits in NMDA receptor activation. We also examined the activation state of afferent pathways in the brainstem that provide excitatory input to the cortex and hippocampus. During lactation, NMA induced c-Fos expression in similar areas of the brainstem as during the cycle, except in the locus coeruleus and dorsal raphe, where c-Fos expression was significantly less than that observed during the cycle. In contrast, no differences in the pattern of c-Fos expression in the brainstem in response to kainate were observed between cycling and lactating rats. The lack of NMA-induced activation of the locus coeruleus and dorsal raphe may contribute to the lack of cortical activation during lactation.

Animals↗
PubMed1994

Antibiotic prophylaxis for urodynamic testing in patients with spinal cord injury: a preliminary study.

This study was performed in order to: (i) determine the incidence of symptomatic urinary tract infection (UTI) in patients with spinal cord injury after urodynamic testing; (ii) evaluate the role of antibiotic prophylaxis for such a procedure; and (iii) investigate whether pre-existing bacteriuria predisposes to the development of symptomatic UTI after urodynamic testing. Forty patients were prospectively randomized in a double-blind fashion to receive a 3-day oral course of either ciprofloxacin (18 patients) or placebo (22 patients), beginning 2 days prior to the urodynamic procedure. None of 18 (0%) patients who received ciprofloxacin developed symptomatic UTI within 5 days after the procedure compared with three of 22 (14%) subjects randomized to the placebo group; the protective efficacy of antibiotic prophylaxis, however, did not attain statistical significance (P = 0.24). None of the three bacterial isolates that were responsible for symptomatic infection were grown in corresponding urine cultures prior to the procedure. These findings may serve as a pilot for a larger study.

Adult↗
PubMed1994

Effectiveness of transnasal butorphanol for the treatment of musculoskeletal pain.

A prospective, open-label study of the effectiveness of transnasal butorphanol in the treatment of pain resulting from musculoskeletal injuries. Twenty-eight patients with strains (n = 20), fractures (n = 6), contusions (n = 1), and stab wounds (n = 1) were included. All patients were examined by an attending level emergency medicine physician and deemed to have pain severe enough to warrant parenteral narcotic analgesia. All patients received an initial 1-mg dose of transnasal butorphanol. Subsequent dosing was flexible depending on response to the initial dose. All patients received pain relief from transnasal butorphanol, and only one requested alternative analgesic medication. Fifty-seven percent (n = 16) of patients noticed at least a little relief of pain within 5 minutes of administration and 93% (n = 26) received at least a little relief within 15 minutes. Seventy-one percent of the patients received a 50% reduction of pain within 60 minutes. No serious side effects were noted, but drowsiness occurred in 82% (n = 23) and dizziness in 54% (n = 15) of the patients. One patient discontinued participation in the study because of nausea. In this limited trial transnasal butorphanol proved to be a rapidly effective opioid analgesic. Further controlled studies comparing transnasal butorphanol with standard parenteral narcotics are needed.

Administration, Intranasal↗
PubMed1994

Long-term persistence of zidovudine resistance mutations in plasma isolates of human immunodeficiency virus type 1 of dideoxyinosine-treated patients removed from zidovudine therapy.

Zidovudine (3'-azido-2',3'-dideoxythymidine)-resistant isolates of human immunodeficiency virus type 1 (HIV-1) were previously demonstrated in zidovudine-treated AIDS patients. The genetic linkage of multiple mutations characteristic of zidovudine resistance as well as dideoxyinosine resistance were demonstrated by examining clones of viral reverse transcriptase after polymerase chain reaction amplification of plasma culture DNA. The zidovudine resistance mutations persisted at seven time points from 4 patients for 5-22 months despite cessation of zidovudine therapy (and while patients underwent dideoxyinosine therapy). One patient's plasma virus isolate at 14 months possessed a genotype doubly resistant to zidovudine and dideoxyinosine. Virus recovered from four time points showed intermediate to high levels of zidovudine resistance. As these genotypes were mainly derived from plasma culture, the zidovudine-resistant virus appears to persist and replicate well in vivo after cessation of zidovudine therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Osmotic inhibition of prolactin secretion in rats.

Chronic hyponatremia is known to cause inhibition of pituitary vasopressin (AVP) and oxytocin (OT) secretion in response to most physiological stimuli, as well as a marked inhibition of synthesis of these peptides. Because many studies have implicated neurohypophyseal peptides in the regulation of pituitary prolactin (PRL) secretion, we investigated the effects of chronic hyponatremia on basal and stimulus-induced PRL secretion in rats. Hyponatremia was induced by subcutaneous infusion of 1-deamino-[8-D-arginine]-vasopressin (dDAVP) (5 ng/h) to rats fed a nutritionally balanced liquid diet, and plasma [Na+] was maintained < or = 115 mmol/l for 10-12 days. After this period, hyponatremic rats and normonatremic controls fed the same diet without dDAVP were subjected to one of the following stimuli known to stimulate PRL release in rats: 3 min exposure to ether, hemorrhage (20 ml/kg), intravenous injection of 5-hydroxytryptophane (5-HTP, 10 mg/kg), or intravenous injection of estradiol (5 micrograms/kg). A baseline blood sample was collected before each stimulus, and 3-6 additional blood samples were collected at selected intervals after the stimulus. Baseline levels of plasma PRL were not different between normonatremic and hyponatremic rats. However, PRL responses induced by either or estradiol, but not those induced by hemorrhage or 5-HTP, were very significantly blunted in the chronically hyponatremic rats. Plasma AVP and OT responses were measured as an index of magnocellular secretion, but did not correlate with the PRL responses for any of the stimuli tested.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Hydroxytryptophan↗
PubMed1994

The use of human lung slices in toxicology.

1. Successful use of agar-filled precision-cut rat lung slices in dynamic organ culture prompted the use of this technology with human lung. 2. The larger tissue mass of a human lung required that the trachea be cannulated with a balloon catheter and subsequently inflated with 4 liters of warm agar/medium mixture and then cooled before being precision-cut into 500 microns thick slices. 3. To characterize the human lung slices, viability and the effects of acrolein and nitrofurantoin were assessed over a period of 24 h using protein synthesis and nonprotein sulfhydryl content. 4. Control human lung slices synthesized protein at a linear rate and maintained a stable nonprotein sulfhydryl content for 24 h. 5. Slices incubated with acrolein exhibited no significant decrease in protein synthesis or nonprotein sulfhydryl levels until 24 h. 6. Incubation with nitrofurantoin exhibited a definite time- and dose-dependent inhibition of protein synthesis, and depletion of the cellular thiol pool. 7. These results indicate that this human lung tissue slice system may be used as an in vitro model to identify and screen pneumotoxicants.

Acrolein↗