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Biomedical subjects

M Davidson

Publications and source records attributed to M Davidson.

At least 163 records · Page 9Linked to original sources
PubMed1995

Transverse vaginal septum. A case report.

A case occurred of imperforate, complete transverse vaginal septum in the lower third of the vagina. The patient presented at 16 years of age with primary amenorrhea and was found to have hematocolpos. The clinical impression was an imperforate hymen because of the very low position of the septum in the vagina. After excision the diagnosis of transverse vaginal septum was made histologically because of the presence of müllerian duct (mesodermal origin) tissue in the septum. The patient also had syndactyly of the second and third toes on her right foot. The association of these two congenital abnormalities has not been reported previously.

Adolescent↗
PubMed1994

Immunogenicity of pneumococcal revaccination in patients with chronic disease.

BACKGROUND: To prevent serious pneumococcal infections, 23-valent pneumococcal polysaccharide vaccine is recommended for individuals over 24 months of age with chronic predisposing diseases and for healthy older adults. This nonrandomized controlled study in rural Alaska assessed the immunogenicity of revaccination in adults. METHODS: Twenty-six adults, 33 to 88 years of age, vaccinated a mean of 7.4 years before this study, were matched to 26 previously unvaccinated subjects by age, number of chronic diseases, sex, and ethnicity. One or more chronic diseases were validated in 62% of subjects (32 of 52). All received a first or second intramuscular dose of pneumococcal vaccine. Antibody levels were determined by radioimmunoassay for 12 pneumococcal capsular serotypes immediately before and 20 to 84 days after vaccination. RESULTS: Six to 9 years after primary vaccination, over one third of serotype-specific antibody levels were below 500 ng of antibody nitrogen per milliliter, equal to the percentage in unvaccinated subjects of similar age. Antibody levels against all pneumococcal serotypes rose to similar levels after primary vaccination and revaccination, and 54% and 55%, respectively, of subjects who received primary vaccination and revaccination had at least a 1.4-fold increase in antibody levels. Only the antibody level for serotype 4 remained low. Neither gender nor age affected peak response. For those with chronic diseases, there was a trend toward fewer low antibody levels against three or more serotypes after revaccination (two subjects [13%]) than after primary vaccination (five subjects [31%]). CONCLUSIONS: Following the initial immunization of high-risk and elderly patients with pneumococcal polysaccharide, pneumococcal antibody levels appear to wane with time. Primary vaccination and revaccination 6 or more years after a first dose of pneumococcal vaccine stimulate comparable mean antibody levels.

Adult↗
PubMed1994

Adverse reactions in cattle to a capripox vaccine.

Capripox vaccine (strain 0240) caused severe generalised skin reactions in vaccinated dairy cattle in two herds, whereas beef cattle did not develop reactions. All the reacting animals developed lumpy skin disease-like lesions. The incidence of skin lesions in first-lactation cows in herd A was 22.9 per cent and in herd B 29.3 per cent, mainly in the post-calving period. In older cows, the incidence was 10 per cent in herd A and 12.4 per cent in herd B. In herd B the high-yielding lactating cows were the most severely affected. There was a decrease of 3.5 per cent in milk production in each herd over a period of 12 days, and six first calving animals (3.5 per cent) and six cows (1.5 per cent) were slaughtered. A capripox virus was isolated from the animals with severe lesions, and was also demonstrated by electron microscopy. The histopathological lesions were similar to those of lumpy skin disease. The extent of the lesions appeared to be stress-related and, to a lesser degree, correlated with age and breed.

Animals↗
PubMed1994

Clozapine treatment and its effect on neuroendocrine responses induced by the serotonin agonist, m-chlorophenylpiperazine.

The effects of clozapine treatment on neuroendocrine responses induced by the serotonin agonist, m-chlorophenylpiperazine (mCPP) were examined. mCPP and placebo were administered after a 2-week drug-free period and again after 5 weeks of clozapine treatment in nine schizophrenic inpatients. Adrenocorticotropic hormone (ACTH), prolactin, and mCPP levels were measured. Clozapine treatment completely blocked mCPP-induced ACTH and prolactin release suggesting that clozapine blocks serotonin receptors that mediate these hormone responses.

Adrenocorticotropic Hormone↗
PubMed1994

Value of metabolic imaging with positron emission tomography for evaluating prognosis in patients with coronary artery disease and left ventricular dysfunction.

Patients with coronary artery disease (CAD) and severe left ventricular (LV) dysfunction have a high but variable annual mortality and some may benefit from myocardial revascularization. This study aimed to evaluate the prognostic value of positron emission tomography (PET), and its interrelation with the choice of medical therapy or revascularization for predicting survival and improvement in symptoms of heart failure in patients with CAD and LV dysfunction. Ninety-three consecutive patients with angiographic CAD and a mean LV ejection fraction of 0.25 who underwent cardiac PET studies for assessment of hypoperfused yet viable myocardium ("mismatch pattern") using N-13 ammonia and 18-F deoxyglucose were followed up for an average of 13.6 months. Fifty patients underwent medical treatment and 43 underwent revascularization. The Cox model analysis showed that the extent of mismatch had a negative effect (p = 0.02), whereas revascularization had a positive effect on survival (p = 0.04). The annual survival probability of patients with mismatch receiving medical therapy was lower than of those without mismatch (50 vs 92%, p = 0.007). Patients with mismatch who underwent revascularization had a higher survival rate than those treated medically (88 vs 50%, P = 0.03). The presence of mismatch also predicted improvement in heart failure symptoms after revascularization (p < 0.001). These results suggest that the presence of mismatch in patients with CAD and severe LV dysfunction is associated with poor annual survival with medical therapy. Revascularization in patients with PET mismatch appears to be associated with improved survival and heart failure symptoms.

Aged↗
PubMed1994

Myocardial viability in asynergic regions subtended by occluded coronary arteries: relation to the status of collateral flow in patients with chronic coronary artery disease.

OBJECTIVES: This study aimed to determine whether angiographically visualized collateral vessels in patients with chronic coronary artery disease imply the presence of viable myocardium in asynergic regions subtended by completely occluded coronary arteries. BACKGROUND: Patients with chronic coronary artery disease who are being considered for revascularization frequently exhibit angiographically visualized collateral vessels to completely occluded coronary arteries supplying severely asynergic myocardial regions. However, little is known about the relation between angiographic collateral flow and myocardial viability in these patients. METHODS: We studied 42 patients with 78 completely occluded coronary arteries supplying asynergic territories. Angiographic collateral vessels were interpreted as absent (grade 1) in 14 patients, minimal (grade 2) in 27 and well developed (grade 3) in 37. Myocardial viability was determined with positron emission tomography using nitrogen-13 (N-13) ammonia and fluorine-18 (F-18) deoxyglucose for assessment of regional perfusion and glucose uptake, respectively. Positron emission tomographic patterns were interpreted as mismatch (perfusion defect with enhanced F-18 deoxyglucose uptake); transmural match (severe concordant reduction or absence of both perfusion and F-18 deoxyglucose uptake) or nontransmural match (mild to moderate concordant reduction of both perfusion and F-18 deoxyglucose uptake). RESULTS: There was no significant correlation (p = 0.14) between the severity of perfusion deficit assessed by positron emission tomography and the collateral grade. The extent of mismatch was unrelated to either the presence or the magnitude of collateral vessels. Conversely, with increasing collateral vessels from grade 1 to 3, the total extent of positron emission tomographic match remained similar, whereas the ratio of transmural to nontransmural match decreased. Myocardial viability was usually present in severely hypokinetic regions (82%). It was lower in akinetic-dyskinetic regions (49%). Of the 64 regions with angiographic collateral vessels, 37 (58%) (95% confidence interval [CI] 46% to 70%) showed positron emission tomographic mismatch. In contrast, 7 (50%) of 14 (95% CI 24% to 76%) regions without collateral vessels on angiography exhibited positron emission tomographic mismatch. The presence of angiographically visualized collateral vessels was a sensitive (84%) but not specific (21%) marker of viability. CONCLUSIONS: In patients with chronic coronary artery disease, angiographically visualized collateral vessels to asynergic myocardial regions subtended by occluded coronary arteries do not always imply the presence of viable myocardium, suggesting that revascularization may not always provide a functional benefit.

Adult↗
PubMed1994

Effects of ipsapirone in healthy subjects: a dose-response study.

A dose-response study of ipsapirone (IPS), a 5HT1a partial agonist, was conducted in healthy male subjects. IPS was administered in doses of 5, 10 and 20 mg PO in a placebo-controlled, double-blind design to 15 subjects on 4 test days separated by at least 3 days. Oral temperature, ACTH, cortisol, prolactin, blood pressure, pulse rate and behavioral variables were assessed every 30 min for 3 h after administration of tablets (at 10:00 A.M.). IPS at 20 mg significantly decreased temperature and increased cortisol levels. Although IPS increased ACTH levels at 20 mg, this effect was variable and not significant. IPS did not affect prolactin levels nor did it have any behavioral effects. Although 20 mg IPS decreased blood pressure and pulse rate in one subject, overall it had no significant effect on these parameters. IPS at 20 mg PO appears a useful probe to test 5HT1a function when temperature and cortisol are used as response variables. These results replicate earlier studies on the effect of IPS in healthy human subjects.

Adrenocorticotropic Hormone↗
PubMed1994

Neuropsychological correlates of central monoamine function in chronic schizophrenia: relationship between CSF metabolites and cognitive function.

Schizophrenia is associated with multiple cognitive deficits which in turn may be related to abnormal dopamine (DA) function. To examine possible associations between cognitive dysfunction and central DA activity in schizophrenia, neuropsychological measures (visuospatial and verbal recall; performance on the Wisconsin Card Sort Test (WCST); visuospatial perception) were examined in 17 drug-free male schizophrenic patients and related to cerebrospinal fluid concentrations of the metabolites of dopamine (homovanillic acid (HVA)), serotonin, and norepinephrine. CSF HVA concentrations were correlated with the ability to recall visuospatial information, with attention to verbal tasks, and with WCST performance (low CSF HVA concentrations predicting poor performance on these tests) but not with the ability to recall verbally presented material and visuospatial perception. These data are consistent with earlier results suggesting that (cortical) DA function is associated with recall and retrieval of visuospatial information and with WCST performance.

Adult↗
PubMed1994

Attentional predictors of clinical change during neuroleptic treatment in schizophrenia.

Improvement in auditory selective attention performance was examined in acute schizophrenic inpatients (n = 13) both off and on medication using the digit span distraction task. Subjects were tested at drug-free baseline and weekly for three weeks during treatment with haloperidol. Improvements in distractability preceded and predicted clinical improvements. A control group of stable schizophrenic outpatients (n = 12) medicated at all testing intervals were examined during the same time period. No significant clinical or attentional changes were found in the control group over the four testing intervals. These results suggest that specific types of attentional functions are intrinsically related to the biological processes affected by neuroleptic treatment and lend preliminary support to the contention that schizophrenic symptoms are mediated by attentional impairment.

Adult↗
PubMed1994

Cortical cholinergic markers in schizophrenia.

Cortical cholinergic deficits have been implicated in the cognitive deficits produced by a variety of neurodegenerative diseases including Alzheimer's disease (AD). Recent studies have suggested that many of the chronically institutionalized geriatric schizophrenic patients are also cognitively impaired. In this postmortem study we compared cholinergic marker activity in six different cortical regions derived from elderly controls, chronically institutionalized geriatric schizophrenic patients, and AD patients. All of the Alzheimer's disease cases met neuropathological criteria for AD, while none of the schizophrenic cases met criteria for AD. Cholinergic marker activity (choline acetyltransferase and acetylcholinesterase) was significantly diminished in the AD cohort but not in the schizophrenic cohort. Additionally, cortical choline acetyltransferase activity was significantly and negatively correlated with Clinical Dementia Rating scores (CDR), whereas no such correlations were evident in the schizophrenic cohort. These results suggest that cognitive deficits in geriatric schizophrenics are not due to diminished cortical cholinergic activity.

Acetylcholine↗
PubMed1994

Plasma homovanillic acid and performance on motor and cognitive tasks in community-dwelling elderly: MacArthur studies of successful aging.

To investigate the dopaminergic correlates of the aging-related motor and cognitive deficits, the dopamine metabolite homovanillic acid (HVA) in plasma was studied in a community-dwelling elderly cohort (n = 141). The results showed that hand-signature time (HST), a measure of bradykinesia, correlated negatively with plasma HVA (r = -0.24, p < .007). Similarities task performance showed a trend-level positive correlation with plasma HVA (r = 0.15, p = .08). Because plasma HVA is derived from several sources including central dopaminergic neurons and both central and peripheral noradrenergic neurons, the noradrenergic metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) in plasma was also measured to indirectly estimate the relationships, with HVA originating from noradrenergic metabolism. Plasma MHPG significantly correlated with similarities scores (r = 0.34, p < .001) but not with HST. The results suggested that the association of HVA with prolonged HST may be related to central dopamine metabolism, but its association with similarities scores may be due to noradrenergic metabolism. The results raise the possibility that prolonged HST may be an indicator of preclinical brain dopamine loss in the elderly.

Aged↗
PubMed1994

Galanin-like immunoreactivity is increased in the postmortem cerebral cortex from patients with Alzheimer's disease.

Galanin is a peptide that is associated with cholinergic neurons of the basal forebrain, and, thus, of interest for the neuropathology of Alzheimer's disease. In the present study, human galanin-like immunoreactivity was measured in postmortem human cerebral cortical tissues by using a homologous radioimmunoassay. In an initial study, six cerebral cortical regions were evaluated from nine elderly controls, 13 neuropathologically verified Alzheimer's disease patients, and 19 elderly schizophrenics. A significant 65% increase in galanin was found in frontal cortex Brodmann area 8 of Alzheimer's disease patients compared with controls. In contrast, cerebral cortical tissues from elderly schizophrenics were not different from those from elderly controls in any region. In a second study, 10 cerebral cortical regions were evaluated from 50 neuropathologically verified Alzheimer's disease patients and nine elderly controls. Concentrations of galanin were increased significantly 26-61% in six of 10 cerebral cortical regions examined (Brodmann areas F8, F44, T20, T21, T36, and P22). Purification of brain extracts by size-exclusion Sephadex G-50 chromatography revealed that human galanin-like immunoreactivity eluted in two peaks of different molecular weights. These studies reveal increased concentrations of galanin in the cerebral cortex of Alzheimer's disease, similar to previous findings in basal forebrain tissue. Because galanin inhibits cholinergic neurotransmission, these findings may have important implications in the understanding of Alzheimer's disease neuropathology and associated cognitive deficits.

Alzheimer Disease↗
PubMed1994

Incidence of invasive cervical cancer preceded by negative screening in high-risk Alaska Native women.

BACKGROUND: Alaska Native women experience higher invasive cervical cancer incidence and mortality rates than US whites despite a long-standing cancer screening programme including recommendations for annual Pap smears. METHODS: To determine the frequency and results of cytological screening preceding their diagnoses, a histological and medical record review was completed for 44 of 46 Alaska Native cases of invasive cervical cancer from a defined population. An interval cancer (no prior dysplasia and a negative screening report within 3 years of diagnosis) was determined for 23 women. Mean number of negative reports during the 3- and 5-year intervals before diagnosis was 1.7 and 2.6 respectively. The age-adjusted incidence rate for all cervical cancer was 24.0/100,000 women/year and for interval cancer with single and multiple negative reports during the 3-year interval before diagnosis it was 11.6, and 9.6 respectively. Sensitivity of a Pap smear to demonstrate dysplasia during the year before diagnosis was 51%. CONCLUSIONS: Annual cytological screening of all Alaska Native women with current methods would provide earlier diagnoses for only an additional 15% of cervical cancer cases. Plausible but unproven explanations include rapid progression through precursor stages of neoplasia or random screening errors. Improved or ancillary screening methods appear necessary.

Adolescent↗
PubMed1994

The prevalence of cervical infection with human papillomaviruses and cervical dysplasia in Alaska Native women.

Alaska Native women historically have high rates of sexually transmitted diseases (STDs) and invasive cervical cancer. Their prevalence of cervical infections with human papillomavirus (HPV) in relation to cervical dysplasia was determined with a commercial dot hybridization test for seven HPV genotypes. Type-specific HPV DNA, similarly distributed between genotype groups 16/18 and 31/33/35, was detected in 234 cervical specimens (21%) from 1126 Alaska Native women seeking routine care and colposcopy or from population-based lists. The prevalence of HPV DNA declined with age and increased with sexual activity and cigarette smoking. It was unrelated to use of oral contraceptives or condoms or to STDs. Relative risks associating HPV with increasing severe grades of cervical dysplasia increased markedly with HPV infection, up to 7.1 for high-risk genotypes 16/18 and 14.4 for coinfection with 31/33/35. These genotypes were detected in 8% of women without dysplasia seeking routine care. Screening for strain-specific HPV DNA may identify women at highest risk for cervical neoplasia.

Adolescent↗
PubMed1994

The epidemiology of invasive pneumococcal disease in Alaska, 1986-1990--ethnic differences and opportunities for prevention.

To assess prevention strategies for pneumococcal disease in Alaska, prospective surveillance during 1986-1990 identified 672 invasive pneumococcal infections, including 315 among Alaska Natives. Age-adjusted annual incidence was 74 per 100,000 for Alaska Natives and 16 per 100,000 for nonnatives. The annual incidence in Alaska Native children < 2 years old was 624 per 100,000; rates of 84 per 100,000 for meningitis and 290 per 100,000 for bacteremic pneumonia were 8-10 times higher than for other US groups. By age 75, cumulative incidence (7%) and mortality (1%) in Alaska Natives were almost 4 times higher than for nonnatives. Only 17% of Alaska Native adults with predisposing conditions and invasive infections previously received pneumococcal vaccine. For Alaska Natives, a proposed heptavalent conjugate pneumococcal vaccine will include serotypes responsible for 85% of invasive isolates from children < 2 years but only 32% of those from adults. The 23-valent polysaccharide pneumococcal vaccine, which contains > 94% of serotypes identified in Alaska Native toddlers and adults, should be used more widely.

Adolescent↗
PubMed1994

Serotype distribution and antimicrobial resistance patterns of invasive isolates of Streptococcus pneumoniae: Alaska 1986-1990.

From January 1986 through December 1990, 672 cases of invasive pneumococcal disease were identified. From these, 574 pneumococcal isolates were recovered from normally sterile sites (blood, cerebrospinal and pleural fluid); 92% were serotypes represented in the 23-valent pneumococcal polysaccharide vaccine. The most common serotypes from children < 2 years old were 4, 6B, 9V, 14, 18C, 19F, and 23F, recovered from 83% of Alaska Native and 75.1% of nonnative children with invasive disease. Moderate penicillin resistance (MIC, 0.1-1.0 micrograms/mL) was found in 3.8% of isolates. All were sensitive to chloramphenicol, vancomycin, rifampin, ceftriaxone, cefotaxime, cephalothin, and cefaclor. However, in the Yukon-Kuskokwim Delta region, 16.9% of isolates were moderately resistant to penicillin, and 10.8% were resistant to erythromycin and 6.2% to trimethoprim-sulfamethoxazole; the number resistant to two or more antibiotics increased significantly during surveillance. All multiply resistant isolates were serotype 6B, and all were from Alaska Native patients < 2 years old.

Adolescent↗
PubMed1994

Effect of age on the immunogenicity of yeast recombinant hepatitis B vaccines containing surface antigen (S) or PreS2 + S antigens.

A single-blind, multicenter, phase II trial of yeast recombinant hepatitis B virus (HBV) vaccines containing surface antigen (S) alone or with PreS2 (PreS2 + S) was conducted in 282 healthy HBV-seronegative adults aged 20-59 years. Each volunteer was randomly assigned to receive HBV vaccine containing 10 micrograms of S or one of three doses of PreS2 plus S: 2 + 10 micrograms, 4 + 20 micrograms, or 8 + 40 micrograms. The level of antibody to HBV surface antigen reached depended on the dose of S, not PreS2, received. In each vaccine group, volunteers 20-39 years old had higher titers of anti-PreS2 and antibody to S than those 40-59 years old. The age-related effect on immune response to HBV vaccination suggests that adults should be immunized against hepatitis B at as early an age as possible and that older persons may need a higher dose or booster immunizations to achieve durable immunity.

Adult↗