Biomedical subjects

J K Dunn

Publications and source records attributed to J K Dunn.

At least 37 records · Page 2Linked to original sources

PubMed1997

Physiologic estradiol replacement therapy and cardiac structure and function in normal postmenopausal women: a randomized, double-blind, placebo-controlled, crossover trial.

OBJECTIVE: To assess the effect of estradiol (E2) replacement therapy on cardiac structure and function in healthy postmenopausal women. METHODS: We conducted a randomized, double-blind, placebo-controlled, crossover study of 31 healthy postmenopausal female volunteer study subjects (55-65 years) using 12 weeks of micronized E2 replacement therapy (2 mg/day). Echocardiography and Doppler techniques were used to assess the cardiac effects of E2 at rest and during graded bicycle ergometry. RESULTS: Crossover analysis demonstrated no carryover effects of estrogen treatment (which increased serum E2 15-fold to 37.6 pmol/L) on the cardiac characteristics measured. Estradiol treatment did not affect measurements of systolic function, diastolic function, left ventricular mass, or pulmonary artery pressure at rest or during bicycle ergometry. Left ventricular end-diastolic volume at rest was slightly higher with E2 treatment (P = .03). However, this change was not reflected by changes in stroke volume, ejection fraction, or cardiac output. CONCLUSIONS: Estrogen replacement therapy, which results in physiologic serum concentrations, does not affect cardiac structure or function in normal postmenopausal women after 12 weeks of treatment.

Aged↗

PubMed1997

Immunohistochemical identification of tumor markers in metastatic adenocarcinoma. A diagnostic adjunct in the determination of primary site.

Adenocarcinoma that metastasizes from an unknown primary site is a significant oncologic problem. With the exception of prostate-specific antigen and thyroglobulin, no single immunohistochemical marker is entirely site-specific. A retrospective study was undertaken to determine whether a panel of markers could accurately predict the site of origin of common metastatic adenocarcinomas. On the basis of reports of their relatively restricted specificity for carcinomas of colon, breast, lung, ovary, and upper gastrointestinal tract (stomach, pancreas, and bile duct), eight markers were selected for simultaneous evaluation: gross cystic disease fluid protein-15, breast cancer antigen 225 (BCA225), B72.3, DF3 (CA15-3), carcinoembryonic antigen (CEA), CA19-9, CA125, and estrogen receptor. The study population consisted of 128 metastatic nonmucinous adenocarcinomas for which the primary site was known. Staining was performed on formalin-fixed, paraffin-embedded tissue using an enhanced-sensitivity avidin-biotin peroxidase complex detection system. The most informative markers were CEA, CA19-9, CA125, and BCA225. With this four-marker panel, the most predictive multiple-marker phenotypes, as determined by a combination of area under the receiver operating characteristic curve, specificity, and percent correct predictions, were CEA+, BCA225-, and CA125- for colon tumors; BCA225+, CEA-, and CA125- for breast tumors; BCA225+, CEA+, and CA19-9- for lung tumors; CA125+ and CEA- for ovarian tumors; and CEA+, CA19-9+, and CA125+ for upper gastrointestinal tract tumors. Overall, these phenotypes correctly predicted the known primary site in 66% of cases. Until single highly sensitive and specific markers are developed for adenocarcinomas other than prostate and thyroid tumors, the origin of a metastatic adenocarcinoma can best be suggested or excluded with clinicopathologic data combined with a panel of selected immunohistochemical markers.

Adenocarcinoma↗

PubMed1997

Effects of lipid lowering therapy on progression of coronary and carotid artery disease.

Recent data have extended the benefit of lipid lowering therapy to patients with only mildly to moderately elevated LDL-cholesterol, which is typical of patients with coronary artery disease. Meta-analysis of clinical trials of statin therapy with similar sample sizes indicated that the LDL-cholesterol level on treatment was as good a predictor of angiographic benefit as was the percentage reduction in LDL-cholesterol. We review evidence that management of triglyceride-rich lipoproteins, HDL, fibrinogen, lipoprotein particle size, LDL-oxidation, and lipoprotein (a) may also favorably influence atherosclerotic progression. Angiographic and arterial ultrasound trials of lipid lowering therapy have demonstrated benefits on disease progression that are consistent with benefits on myocardial infarction, stroke, and death reported in larger, lengthier trials.

Arteriosclerosis↗

PubMed1997

Screening for 185delAG in the Ashkenazim.

A study was initiated to assess interest, educational effectiveness, and implications of genetic testing for the common BRCA1 mutation, 185delAG, in the Ashkenazim. Of 333 individuals who attended group sessions, 309 (92%) participated in the study. Participants were categorized as having negative family history (67%), positive family history (defined, by a relaxed criterion, as one first-degree relative or two second-degree relatives with breast [premenopausal] or ovarian cancer) (22%), positive personal history (7%), and both positive personal history and positive family history (4%). Group education was effective, as shown by the improvement in participant scores from pre- to posteducation tests. For the 289 individuals (94%) who requested testing, the major reasons included concern for their own risk, concern for the risk of their children, and desire to learn about surveillance options. The most common reason given by participants who declined testing was concern about health insurance. Six participants found to be heterozygous for the 185delAG mutation received results and were offered genetic counseling. Participants had consented for additional testing without receiving results and were screened for the 6174delT mutation in BRCA2, and seven were found to be positive. All identified carriers reported at least one first- or second-degree relative with a history of breast or ovarian cancer, although they did not all meet our study criteria for positive family history. Given these outcomes, we conclude that screening for breast and ovarian cancer susceptibility is most appropriate for individuals with a positive personal or positive family cancer history. We propose a guideline for future studies designed to identify individuals who may benefit from genetic testing for inherited breast and ovarian cancer.

Adult↗

PubMed1996

Role of chronic disseminated intravascular coagulation in a case of canine angiostrongylosis.

A dog whose major clinical signs suggested a coagulopathy, is described. The dog had a history of bleeding episodes and had a severe regenerative anaemia. By using specific factor assays, the coagulopathy was found to be due to a consumptive intravascular process that resembled chronic disseminated intravascular coagulation. Subsequent investigations identified Angiostrongylus vasorum as the cause.

Anemia↗

PubMed1996

Natural history, determinants, and clinical relevance of conduction abnormalities following orthotopic heart transplantation.

To study the long-term evolution, determinants, and clinical relevance of the conduction abnormalities after orthotopic heart transplantation, 87 patients, followed for a mean of 105 +/- 72 weeks, were divided into 3 groups according to the characteristics of their electrocardiograms compared with their initial electrocardiogram recorded at study entry. The first group consisted of 24 patients whose initial electrocardiogram was normal, and subsequent electrocardiograms remained normal throughout the study. The second group included 27 patients who developed electrocardiographic evidence of progressive conduction system damage. The third group comprised 36 patients whose initial electrocardiogram was abnormal and subsequent electrocardiograms remained unchanged during follow-up. Although the hemodynamic and echocardiographic evaluation of right and left ventricular function were initially similar among the 3 groups, groups 2 and 3 demonstrated a significant deterioration of left ventricular ejection fraction (62 +/- 12% to 55 +/- 16% and 62 +/- 8% to 57 +/- 14%, respectively; p < 0.05) and cardiac index (2.7 +/- 0.6 to 2.3 +/- 0.5 and 3.0 +/- 0.9 to 2.5 +/- 0.9 L/min/m2, respectively; p < 0.05) while patients in group 1 maintained their normal baseline indices. Incidence and progression of coronary artery disease, as well as frequency of rejection episodes, were comparable among the groups. Mortality was higher in the 2 groups with evidence of conduction defects. Sudden death associated with complete heart block (2 patients) or ventricular arrhythmias (3 patients) was exclusively confined to patients with evidence of progressive electrocardiogram abnormalities. We conclude that, following orthotopic heart transplantation, stable or progressive conduction system damage on the electrocardiogram is associated with left ventricular dysfunction and increased mortality. Sudden death is not uncommon among patients demonstrating worsening cardiac conduction and, in some cases, is related to the development of potentially preventable complete heart block.

Adult↗

PubMed1995

Use of ACTH stimulation tests to monitor the treatment of canine hyperadrenocorticism.

The case histories of 60 dogs with hyperadrenocorticism were reviewed. Fifty-four of the dogs were treated with mitotane at a mean daily dose rate of 48.8 mg/kg (range 25.6 to 84 mg/kg) for between four and 21 days. The mean weekly maintenance dose of mitotane was 48.8 mg/kg. An adrenocorticotrophic hormone (ACTH) stimulation test was performed before the treatment began, and in 30 cases at the end of the induction course, and the response to ACTH was measured at regular intervals thereafter. Nine of the treated dogs developed complete hypoadrenocorticism during treatment and required permanent mineralocorticoid replacement therapy. Twelve of the dogs had normal responses to an ACTH stimulation test before treatment, and the diagnosis of hyperadrenocorticism was based on the result of a low-dose dexamethasone suppression test. These 12 dogs had consistently lower cortisol levels before and after stimulation with ACTH and four of them developed complete hypoadrenocorticism. In general the clinical signs were well controlled when the cortisol levels were less than 105 nmol/litre before and after the stimulation test. Dogs in which the clinical signs recurred had cortisol levels between 210 and 580 nmol/litre after the test, a level which is within the normal pretreatment range. Twenty-seven of the treated dogs died and six of these deaths were attributable directly to the disease or therapy. The median survival time of the 54 treated dogs was 30 months; eight dogs died during the first 16 weeks of treatment, and the dogs which survived this period had a median survival time of 39 months (mean 50 months).

Adrenal Cortex Function Tests↗

PubMed1995

Intracranial haemorrhage in a dobermann puppy with von Willebrand's disease.

Neurological examination of a lethargic, ataxic 12-week-old dobermann revealed decreased conscious proprioception in all its limbs. Haematological examination revealed a low platelet count. Cytological examination of a sample of cerebrospinal fluid revealed evidence of haemorrhage and chronic inflammation. The levels of von Willebrand's factor antigen were extremely low. Skull radiographs were consistent with mild hydrocephalus. Treatment resulted in little clinical improvement and the animal was euthanased. Post mortem examination of the brain revealed an internal hydrocephalus with haemorrhage into the ventricles. It was considered that the animal had suffered severe intracranial haemorrhage as a result of its low level of von Willebrand's factor antigen and that the bleeding may have been potentiated by the low platelet count.

Animals↗

PubMed1995

Is prostate-specific antigen density more useful than prostate-specific antigen levels in the diagnosis of prostate cancer?

OBJECTIVES: To compare the performance of prostate-specific antigen (PSA) levels with the performance of PSA density (PSAD), the ratio of the serum to the size of the prostate, as predictors of the presence of prostate cancer. METHODS: We analyzed the results of digital rectal examination (DRE), transrectal ultrasonography (TRUS), serum PSA levels, and PSAD in 244 patients who had a needle biopsy of the prostate. RESULTS: Cancer was detected in 110 patients (45%). Compared with DRE, TRUS and serum PSA levels 4.0 ng/mL or higher, PSAD at a cutoff point of 0.15 ng/mL/cm3 was significantly more specific and had a higher positive predictive value than each of the other tests but was significantly less sensitive than TRUS and PSA (P < 0.05 for each). In a receiver operating characteristic analysis, PSAD was significantly more accurate than PSA (P < 0.001). In 80 patients with a normal PSA, PSAD added no additional information, and PSAD was not able to identify a subset at low risk. In 82 patients with a high PSA level (10 ng/mL or higher), 15% had a PSAD less than 0.15 and only 8% had a cancer. CONCLUSIONS: Overall, PSAD was significantly more accurate than PSA for predicting the results of needle biopsy of the prostate, but in practice PSAD proved useful in only a small subset of patients. If the serum PSA level was high but the PSAD was low, cancer was rarely detected. These patients may be suitable candidates for careful follow-up rather than early repeat biopsy.

Aged↗

PubMed1995

Selective dendritic alterations in the cortex of Rett syndrome.

Rett syndrome, the commonest condition associated with severe mental retardation in girls, is diagnosed only by its clinical phenotype, because, to date, there is no consistent characteristic alteration in genetic, biochemical, neurotransmitter or morphologic marker. The clinical features at various ages suggest involvement of most parts of the nervous system, however, the brain in Rett syndrome is reduced in weight, without other obvious morphologic alterations. Because of the relative microcephaly, hypotheses regarding failure of development have been suggested. Supporting such hypotheses are the quantitative studies by Jellinger, Seitelberger and Kitt defining a decrease in the amount of melanin in the substantia nigra and by Bauman defining a global decrease in the size of the neurons. In this study the cerebral cortex has been examined using the rapid Golgi technique with the purpose of investigating dendrites of pyramidal neurons in six cortical regions of Rett girls from ages 2.9-35 years. Camera lucida drawings of apical and basal dendrites of two cortical layers and CA1 were prepared. These were submitted to the Sholl analysis. The Sholl analyses were tested for significance using the repeated measures analysis of covariance, with age as a covariate. The studies demonstrate that from our samples there is no evidence that the pyramidal neurons in Rett syndrome degenerate progressively with increasing age but that the basal dendrites of layers three and five pyramidal neurons in the motor and frontal cortex, the apical dendrites of layer five of the motor cortex, and the basal dendrites of layer four of the subiculum are significantly shorter than in non-Rett brains.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Effects of beef and chicken consumption on plasma lipid levels in hypercholesterolemic men.

BACKGROUND: The recommendation to lower saturated fat intake is often interpreted as requiring the elimination of beef to control or lower serum cholesterol levels. The study hypothesis was that the Step I Diet (8% to 10% of energy intake from saturated fatty acids) containing beef would have the same effect on plasma lipid levels of hypercholesterolemic men as a like diet containing chicken. METHODS: Thirty-eight free-living hypercholesterolemic (otherwise healthy) men completed a 13-week dietary intervention study. Subjects consumed their usual diets for 3 weeks, followed by a 5-week stabilization diet (18% of energy intake from saturated fatty acids), before randomization to one of two test diets for 5 weeks. The test diets contained either 85 g of cooked beef (8% fat) or 85 g of cooked chicken (7% fat) per 4184 kJ and had 7% to 8% of energy from saturated fatty acids. All food was supplied during the stabilization and test diets. RESULTS: The beef and chicken test diets both produced significant decreases in average plasma total cholesterol level (0.54 mmol/L [7.6%] for beef and 0.70 mmol/L [10.2%] for chicken) and low-density lipoprotein cholesterol level (0.46 mmol/L [9%] for beef and 0.55 mmol/L [11%] for chicken). Changes in average levels of plasma total cholesterol, high-density lipoprotein cholesterol, triglyceride, and low-density lipoprotein cholesterol were not statistically different (smallest P = .26) between the beef and chicken test diets. The average triglyceride level did not change for either test diet group. CONCLUSIONS: In this short-term study, comparably lean beef and chicken had similar effects on plasma levels of total, low-density lipoprotein, and high-density lipoprotein cholesterol and triglyceride. We concluded that lean beef and chicken are interchangeable in the Step I Diet.

Adult↗

PubMed1994

Frequency of apoptotic bodies positively correlates with Gleason grade in prostate cancer.

Tissue samples from patients with carcinoma of the prostate of various Gleason grades were examined for the frequency of apoptotic bodies. Apoptotic bodies were scored by morphometric methods using hematoxylin-eosin (HE)-stained sections from surgical specimens of prostate cancer. Non-neoplastic prostate tissue adjacent to foci of cancer showed a very low frequency of apoptotic bodies. Significantly larger numbers of apoptotic bodies were observed in the areas of carcinoma than in the non-neoplastic control tissues, regardless of Gleason grade. Interestingly, a positive correlation was noted between apoptotic bodies and increasing Gleason grade. The positive correlation suggests that increased programmed cell death is a feature of the increasing malignant potential that is associated with higher Gleason grade in prostate cancer.

Adult↗

PubMed1994

Electrocardiographic findings in Rett syndrome: an explanation for sudden death?

Girls with Rett syndrome had significantly longer corrected QT intervals (p < 0.001) and more T-wave abnormalities (p < 0.001) than were found in age-matched healthy girls. With advancing stages of the syndrome, the proportion of corrected QT interval prolongations and T-wave changes increased. The findings suggest a possible cardiac basis for sudden, unexpected death in Rett syndrome.

Adolescent↗

PubMed1994

The pathological features and prognosis of prostate cancer detectable with current diagnostic tests.

The discrepancy between the high prevalence of prostate cancer found at autopsy and the low incidence of clinical cancer prompted a study to determine whether the new diagnostic tests, that is ultrasonography and serum prostatic specific antigen (PSA) levels, detect prostate cancer at an earlier stage than the traditional test, digital rectal examination, without detecting a larger proportion of clinically unimportant cancer. Clinically detected cancer treated by radical prostatectomy (306 cases) and incidental cancer found in cystoprostatectomy specimens (90) were categorized into 3 groups by the volume, grade, extent of the cancer and outcome of treatment: clinically unimportant tumor (0.5 cm.3 or less, Gleason grades 1 to 3 and confined to the prostate), clinically important curable cancer (more than 0.5 cm.3 or grade 4 or 5 and confined, or with microscopic extracapsular extension) or advanced disease (extensive extracapsular extension, seminal vesicle invasion or lymph node metastases). Of 306 clinically detected tumors 9% were unimportant and 29% were advanced. In contrast, incidental cystoprostatectomy disease was either unimportant (78%) or curable (22%) and no tumor was advanced (p < 0.0005). Cancer detectable by digital rectal examination, ultrasonography or PSA was distributed similarly among the 3 groups. Impalpable cancer detected by PSA was less likely to be advanced (11%) than cancer detected by digital rectal examination (34%, p = 0.01) but no more likely to be unimportant (13% versus 8%). Of 29 tumors detected only by systematic biopsies because of an elevated PSA level only 4% were advanced, while 17% were unimportant. Cancer detectable with each of the available diagnostic tests was similar and differed distinctly from that found incidentally in cystoprostatectomy specimens. The detection of impalpable cancer by PSA or ultrasound decreased the proportion of advanced tumor detected without increasing significantly the detection of unimportant disease.

Adult↗

PubMed1994

alpha-Difluoromethylornithine delays behavioral recovery and induces decompensation after unilateral labyrinthectomy.

Biochemical and pharmacologic studies suggest a role for the ornithine decarboxylase-polyamine system as a modulator of behavioral changes during vestibular compensation. alpha-Difluoromethylornithine specifically blocks the rate-limiting step of polyamine biosynthesis. To assess the effects of alpha-difluoromethylornithine on the acute phase of postural compensation, guinea pigs were divided into groups subjected to either unilateral labyrinthectomy only (n = 7), alpha-difluoromethylornithine (500 mg/kg/day) for 4 days before labyrinthectomy (n = 10), equivalent volumes of saline for 4 days before labyrinthectomy (n = 8), and sham operations (n = 5). Yaw head tilt and roll head tilt, trunk curvature, and air-righting reflex were measured at baseline and at regular intervals up to 4 weeks. alpha-Difluoromethylornithine significantly delayed recovery of normal air-righting but had no effect on yaw head tilt, roll head tilt, and trunk curvature. We also evaluated effects of alpha-difluoromethylornithine in compensated guinea pigs. Fully compensated animals from phase 1 were randomly assigned to receive alpha-difluoromethylornithine (500 mg/kg/day) or saline once daily for 4 days. Only 33% of alpha-difluoromethylornithine animals maintained air-righting, compared with 100% of saline-treated animals (p = 0.003). Maximum trunk curvature was greater in the alpha-difluoromethylornithine group (p = 0.02). Thus alpha-difluoromethylornithine not only delayed the time course for postural recovery after unilateral labyrinthectomy, it also transiently disrupted the maintenance of the compensated state.

Animals↗

PubMed1993

Once-daily, extended-release gemfibrozil in patients with dyslipidemia. The Lopid SR Work Group I.

This randomized, parallel-group, multicenter clinical trial compared a newly developed, once-daily, extended-release formulation of gemfibrozil (Lopid SR) and gemfibrozil twice daily (Lopid) in terms of lipid-regulating effects and toxicity. Patients were men and women with elevations of low-density lipoprotein cholesterol and low levels of high-density lipoprotein cholesterol. The trial consisted of a 1-week screening period, an 8-week diet baseline period (Step One Diet), and a 24-week double-blind treatment period (extended-release gemfibrozil 1,200 mg once daily vs gemfibrozil 600 mg twice daily). At the end of the trial, the 2 treatment groups showed comparable improvements in all primary lipid factors: mean percent changes in triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were -32, +10 and -10% for extended release (n = 325) and -36, +11 and -10% for twice daily (n = 330). The 90% confidence interval for the relative difference between the treatment means fell within the equivalence bounds of +/- 35% for all 3 factors, demonstrating equivalence of efficacy. Adverse events were reported at low rates and were similarly distributed in frequency and intensity between treatment groups; they were preponderantly mild or moderate, and gastrointestinal effects were the most frequent. The once-daily formulation of gemfibrozil may afford better control of dyslipidemia through improved compliance by patients who have this asymptomatic disease.

Adolescent↗

PubMed1993

The incidence of perioperative myocardial infarction in men undergoing noncardiac surgery.

OBJECTIVES: To determine the incidence of and risk factors for perioperative myocardial infarction with noncardiac surgery and to test the accuracy of a risk stratification system. DESIGN: Prospective cohort study. SETTING: A large urban Veterans Affairs hospital. PARTICIPANTS: A total of 1487 men older than 40 years undergoing major, nonemergent, noncardiac operations. MEASUREMENTS: Infarction was established by at least two of the following: development of new Q waves, typical change in creatine kinase MB, and positive technetium pyrophosphate scintigraphy. Patients were stratified preoperatively into high-, intermediate-, low-, and negligible-risk strata based on clinical markers corresponding to different levels of coronary artery disease prevalence. MAIN RESULTS: Patients with coronary disease (high-risk stratum) had a 4.1% incidence of infarction (13 of 319; 95% CI, 1.8% to 6.4%); patients with peripheral vascular disease but no evidence of coronary disease (intermediate-risk stratum) had a 0.8% incidence (2 of 260, upper bound of CI, 2.0%); patients with high atherogenic risk factor profiles but no clinical atherosclerosis (low-risk stratum) had a 0% incidence (0 of 256, upper bound of CI, 1.2%). No cardiac deaths occurred in 652 men who had no atherosclerosis and low atherogenic risk factor profiles (the negligible-risk stratum). Factors independently associated with infarction included age more than 75 years (adjusted odds ratio, 4.77; CI, 1.17 to 19.41), signs of heart failure on the preoperative examination (adjusted odds ratio, 3.31; CI, 0.96 to 11.38), coronary disease (adjusted odds ratio, 10.39; CI, 2.27 to 47.46), and a planned vascular operation (adjusted odds ratio, 3.72; CI, 1.12 to 12.37). CONCLUSIONS: Coronary artery disease is the major risk factor for perioperative infarction. The stratification scheme identifies subsets of patients with different risks, and finer within-stratum distinctions can be made using additional variables.

Adult↗

PubMed1993

Advance directives on hospital admission: a survey of patient attitudes.

A survey of 200 outpatients using an anonymous, self-administered questionnaire revealed that 18% had already completed an advance directive. Only 5% had received information concerning advance directives from their physicians. Eighty-seven percent stated they would not be offended if, on admission to the hospital, they were to be asked whether they had completed a living will. Eighty-eight percent would view such a policy as showing evidence of positive concern by the hospital on their behalf. Only 2% consistently gave a negative response to a proposed policy of hospitals providing information concerning advance directives on admission, and a similar percentage was totally opposed to their use. Of those who had completed an advance directive, 50% had secured the only copy in a safety deposit box. This information, as well as the Patient Self-Determination Act of 1990, which will as of December 1, 1991 require hospitals to provide patients with information about advance directives, creates a new framework for the more efficient use of these important but underused documents.

Adolescent↗