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Biomedical subjects

M Miller

Publications and source records attributed to M Miller.

At least 109 records · Page 6Linked to original sources
PubMed2001

Presumptive copper deficiency in hand-reared captive pronghorn (Antilocapra americana) fawns.

Presumptive copper deficiency was diagnosed in hand-reared captive pronghorn (Antilocapra americana) at the Los Angeles Zoo. Clinical signs, which were manifested in growing fawns, included anemia, anorexia, diarrhea, progressive paresis/recumbency, and aortic rupture. The range of serum copper concentrations in fawns born during the 1989 season (0.08-0.67 ppm) was below levels considered normal for domestic sheep and goats (0.7-2.0 ppm) and below concentrations measured in adult pronghorn (0.4-1.43 ppm). Copper sulfate supplementation of the hand-rearing formula, which was initiated in 1989, resulted in a significant increase in mean (+/- SD) serum copper levels from 0.45 +/- 0.18 ppm before supplementation to 0.68 +/- 0.05 ppm after supplementation (P < 0.05). Fawns born in subsequent seasons (April 1990-August 1993) continued to be supplemented with copper in the hand-rearing formula. Mean serum copper concentration from these fawns (0.68 +/- 0.22 ppm) was similar to the mean values from supplemented 1989 fawns and adult pronghorn in this herd (0.85 +/- 0.34 ppm; P > 0.05). No clinical signs of copper deficiency were detected in any fawns after supplementation was started. Analyses of the herd's diet revealed marginal dietary copper levels. Suspected dietary deficiency was confirmed by marginal tissue and serum copper concentrations in some of the herd's adult animals. Dietary copper levels were corrected to prevent future cases of clinical copper deficiency.

Aortic Dissection↗
PubMed2001

Glutaraldehyde-induced colitis.

OBJECTIVE: To describe the etiology and clinical course of acute colitis occurring after flexible endoscopy. DESIGN: Chart review. SETTING: A university teaching hospital. PATIENTS: Eight patients who sought assessment of potential colonic disease. INTERVENTION: Colonoscopy in 5 patients and flexible sigmoidoscopy in 3 patients. The indication for endoscopy was screening in 5 patients, cancer surveillance in 2 patients and preoperative evaluation of colon carcinoma in 1 patient. OUTCOME MEASURES: The relation of presenting symptoms to glutaraldehyde exposure, the response to therapy and the need for further therapy. RESULTS: All patients had abdominal pain, mucus diarrhea and rectal bleeding within 48 hours after endoscopy. Most patients reported that the symptoms started within 12 hours of the procedure. All patients were confirmed by sigmoidoscopy to have colitis within 72 hours of the first endoscopic procedure. One patient required hospitalization. In the first 7 patients several stool cultures were negative for Clostridium difficile using the cytotoxin assay by the cell culture method. Four patients had negative cultures for Yersinia, Salmonella and Shigella spp. Three patients were treated with metronidazole initially. Two patients underwent endoscopic biopsy and examination of the biopsy specimen showed fibrinoleukocytic exudate and ischemic type injury. One patient underwent the scheduled sigmoid resection within 48 hours of endoscopy for a Dukes' stage B adenocarcinoma. Concomitant acute ischemic colitis limited to the mucosa and submucosa was noted in the resected specimen. Symptoms resolved in all patients and follow-up endoscopy revealed normal mucosa. CONCLUSION: The entity of glutaraldehyde-induced colitis should be recognized and special attention should be given during instrument cleansing to minimize the risk of its development.

Acute Disease↗
PubMed2001

Conventional coronary artery bypass grafting: why women take longer to recover.

BACKGROUND: Recovery following successful coronary artery bypass grafting (CABG) has been dramatically improved with the use of fast-track methods. Although data exist that demonstrate a significant gender difference in survival following CABG, little is known about factors influencing gender-specific recovery. This report describes a series of consecutive patients undergoing isolated CABG to determine gender-associated factors that may impact outcomes and recovery. METHODS: Five hundred and seventeen consecutive patients underwent isolated CABG utilizing cardiopulmonary bypass and were retrospectively reviewed. The outcomes of 351 men in the study were compared to the group of 160 women. A rapid recovery protocol focused on reduced cardiopulmonary bypass time, aggressive preoperative intra-aortic balloon pump use, early extubation, perioperative administration of corticosteroids and thyroid hormone, aggressive diuresis and atrial fibrillation prevention was applied to all patients. RESULTS: The 30-day mortality rate for the women was 4.2% (Parsonnet risk 16.3+/-9.0) compared with 3.4% (Parsonnet risk 9.9+/-7.5) for the men. There were no statistically significant differences in the 30-day mortality rates or postoperative complication rates between the women and men. The women, however, were found to be older (71+/- years versus 65+/- years, p<0.001), and to have a higher incidence of acute myocardial infarction (31% versus 20%, p<0.05), obesity (23% versus 10%, p <0.05), diabetes (31% versus 22%, p<0.05), hypertension (65% versus 48%, p<0.001), and symptomatic vascular disease (20% versus 12%, p<0.05). The women required fewer bypass grafts (2.9 versus 3.5 grafts, p<0.001), and consequently, had shorter cross and cardiopulmonary bypass times. Rapid recovery with discharge before the fifth postoperative day was achieved in 30% of the women, in comparison to 44% of the men (p<0.01). The postoperative hospital length of stay was longer for the women in comparison to the men (7.2+/-7.1 versus 5.8+/-5.2 days, p<0.05). CONCLUSIONS: Women had similar operative mortality and postoperative complication rates to men under a rapid recovery protocol. However, women have a longer recovery interval compared to men, which may be a reflection of their higher preoperative risk profile.

Age Factors↗
PubMed2001

Antimicrobial sensitivity of Haemophilus influenzae isolates from bacterial conjunctivitis.

Haemophilus influenzae is one of the common bacterial pathogens which affect children. Resistance to frequently used antibiotics is becoming a significant problem in community isolates of common pathogens. A retrospective review was conducted of the serotypes and antimicrobial sensitivity of H influenzae isolates from bacterial conjunctivitis, over an 18-month period. Data on antimicrobial sensitivity (obtained by the National Committee for Clinical Laboratory Standards disk diffusion method) and beta-lactamase production, and typing results, were analysed. Ninety-nine isolates were recovered, of which 87 were typed. Most isolates were recovered from children under one year of age. Ninety-three percent were unencapsulated and biotypes I and IV were most common. H influenzae type b was recovered only twice. beta-lactamase was produced by 41% isolates while four isolates were ampicillin-resistant but did not produce beta-lactamase. All isolates were sensitive to chloramphenicol and 45% were co-trimoxazole sensitive. H influenzae is commonly isolated from bacterial conjunctivitis in Barbados and, as elsewhere, the majority of isolates are from small children and are non-encapsulated. However, there is a high prevalence of beta-lactamase production, which may serve as a reservoir for transfer to more invasive encapsulated strains of H influenzae within the oropharyngeal flora.

Adult↗
PubMed2001

39-day delay in delivery of twins. A case report.

BACKGROUND: Delayed delivery is a rare occurrence in the literature despite advances in reproductive technology and increasing numbers of multiple gestations. CASE: A 30-year-old woman, gravida 2, para 0010, presented at 23 weeks and 3 days' gestation with a twin pregnancy. An interval of 39 days was achieved between delivery of the first and second fetus with aggressive tocolysis and antibiotic therapy. Follow-up at three years revealed the second twin to be a fully functioning boy. CONCLUSION: Forty citations in the literature have examined delayed delivery. With careful patient selection and thorough patient counseling, delayed delivery offers a safe and beneficial management option for selected multiple gestations.

Adult↗
PubMed2000

Differentiating the effects of raising low levels of high-density lipoprotein cholesterol versus lowering normal triglycerides: further insights from the Veterans Affairs High-Density Lipoprotein Intervention Trial.

In the Veterans Affairs High-Density Lipoprotein Intervention Trial (VA-HIT), a 6% increase in high-density lipoprotein cholesterol (HDL-C) was associated with a 22% reduction in the incidence of fatal and nonfatal myocardial infarction and death from coronary artery disease. A curvilinear correlation was demonstrated between incremental changes in HDL-C and outcome. However, triglyceride levels, which decreased by 31%, were not predictive of clinical events. Some design limitations may be implicated in this lack of statistical correlation between triglycerides and outcome. Evidence from other studies, notably the Framingham Heart Study, the Prospective Cardiovascular Munster Heart Study (PROCAM), and the Baltimore Coronary Observational Long-Term Study (COLTS) suggest that the triglyceride cutpoint of 200 mg/dL is too high. The Bezafibrate Infarction Prevention (BIP) trial found a significant correlation between reduction in death from coronary artery disease and nonfatal MI and reduced triglycerides in a subset of patients with baseline triglycerides >200 mg/dL.

Aged↗
PubMed2000

Working without accumulation membrane in flow field-flow fractionation.

Nonideal interaction of sample with the separation device is a difficulty found in chromatographic methods as well as in field-flow fractionation. However, in field-flow fractionation (FFF), greater flexibility in the choice of carrier solution composition is possible, thus reducing the need of a wide choice of surface chemistry when nonideal sample interaction is to be minimized. The use of an ultrafiltration membrane as the surface for the accumulation wall is common practice in flow field-flow fractionation. Typical membranes in use are laminates of a skin membrane onto a backing material such as woven polyester. At this point, only a limited choice of membrane chemistries is available. Many membranes have been developed for protein applications as membranes are widely used in the pharmaceutical industries. While these membranes work well for protein applications, flow field-flow fractionation is applicable to polymeric particulate as well as protein samples. Thus, sample interaction with the membrane surface is possible with nonprotein applications and these interactions can induce significant secondary effects on retention ratio and affect instrumental reliability. Also, the woven texture of membranes may detrimentally affect the FFF separation. For these reasons, the study of flow field-flow fractionation using a flat, smooth surface of controlled chemistry is of relevance. We present here the results of a new, membraneless channel that uses a bare frit as the accumulation wall and that is intended for analysis of micrometer-sized particles only. Selectivity results are comparable to those obtained with the membrane, while relative sample recovery indicates that the best quantitative performance can be obtained without the membrane. Moreover, neither sample immobilization nor losses through the frit occur when operating membraneless. On the other hand, first experimental evidence of a certain level of frit surface activity suggests that optimization of experimental conditions is required.

Journal Article↗
PubMed2000

Sakurai addition and ring annulation of allylsilanes with alpha, beta-unsaturated esters. Experimental results and ab initio theoretical predictions examining allylsilane reactivity

Trimethylallylsilane has been shown to add to methyl acrylate in good yield when catalyzed by TiCl(4) at room-temperature despite literature reporting to the contrary. Further, even with these small alkyl ligands on the metal, ring annulation occurs to a large extent, in addition to simple allylation (Sakurai addition). The kinetic product is the ((trimethylsilyl)methyl)cyclobutane derivative which can be isomerized to cyclopentanoid, the thermodynamic product, if left in the presence of the catalyst. Consistent with other literature in this area, increasing the size of the ligands on silicon increases both the rate of product formation and the proportion of ring annulation relative to allylation. To develop a predictive model for allylsilane reactivity, ab initio gas-phase calculations have been made on the parent allylsilane with different ligands on the metal and on the reaction between these allylsilanes and acrolein, acrylic acid, and methyl acrylate. Predictions indicate that as the length of n-alkyl ligands on silicon increase, so does the apparent ability of the Si-Calpha bond of the allylsilane to hyperconjugate with developing vacant p orbital on Cbeta as the allylsilane begins to attack an electrophile. This is corroborated by a gradually increasing HOMO in the ground-state allylsilane as the ligands are changed from methyl through to n-hexyl and an increasing Si-Calpha bond length and decreasing Si-Calpha-Cbeta bond angle in the protonated species. These results in the gas phase mirror the reactivity of these n-alkyl-substituted allylsilanes in experiment; i.e., as the length of the alkyl chain increases, reactivity increases significantly. Triisopropylallylsilane, a very reactive silane, appears to anomalous in charge distribution and geometrical features compared with other substituted allylsilane systems which is due, presumably, to steric effects. The calculations on the protonated species would indicate that almost no hyperconjugative stabilization can occur on the basis of the bond lengths and angles necessary to promote good orbital overlap between the Si-Calpha bond and the empty p orbital on Cbeta. However, the gas-phase reaction of the triisopropylallylsilane with acrolein and methyl acrylate led to comparatively low energy barriers of 13.1 and 24.5, respectively, which is consistent with its high experimental reactivity. Together, this computational analysis has produced a useful model for predicting allylsilane reactivity and some possible explanations for this reactivity.

Journal Article↗
PubMed2000

Cigarette smoking and suicide: a prospective study of 300,000 male active-duty Army soldiers.

The authors examined the relation between cigarette smoking and suicide by conducting a cohort study of 300,000 male US Army personnel followed prospectively from January 1987 through December 1996 for 961,657 person-years. They found that the risk of suicide increased significantly with the number of cigarettes smoked daily (p for trend < 0.001). In multivariable-adjusted analyses, smokers of more than 20 cigarettes a day, compared with never smokers, were more than twice as likely to commit suicide. For male active-duty army personnel, the dose-related association between smoking and suicide was not entirely explained by the greater tendency of smokers to be White, drink heavily, have less education, and exercise less often.

Adult↗
PubMed2000

Chest pain with nondiagnostic electrocardiogram in the emergency department: a randomized controlled trial of two cardiac marker regimens.

BACKGROUND: Early detection of acute myocardial infarction (AMI) may save lives. In the emergency setting, it is unclear whether the early use of certain cardiac markers (myoglobin and cardiac troponin I [cTnI]) assists in making appropriate decisions whether to admit or discharge patients with chest pain of possible ischemic cause who have nondiagnostic electrocardiograms (ECGs). We performed a study to determine whether the addition of new cardiac markers in the emergency department results in improved clinical decisions. METHODS: A single-blind randomized controlled trial was conducted between June 1997 and June 1998 in a tertiary care emergency department in Kingston, Ont. Of 296 patients aged 30 years or more who presented to the emergency department with chest pain and nondiagnostic ECGs, 146 were randomly assigned to the intervention group (determination of baseline creatine kinase [CK] level, CK MB fraction and cTnI level, and myoglobin level at baseline and at 2 hours) and 150 to the control group (determination of baseline CK level and CK MB fraction). Outcome measures included the rate of admission to the inpatient cardiology service and length of stay in the emergency department. RESULTS: Of the 296 patients, 34 (11.5%) received a diagnosis of AMI in the emergency department, and 92 (31.1%) had chest pain of noncardiac cause. Patients in the intervention group were less likely than those in the control group to be admitted to the cardiology service (67 [45.9%] v. 81 [54.0%]). The absolute difference in the proportion (8.1% [95% confidence interval -3.3 to 19.5]), although potentially important clinically, was not statistically significant. The length of stay in the emergency department was essentially the same in the 2 study groups. At 30 days, the proportions of patients with a diagnosis of recurrent angina (58.2% in the intervention group and 58.0% in the control group) and AMI (12.3% and 14.7%) were also similar. INTERPRETATION: The optimal cardiac marker panel to be used in the emergency department remains unknown. The addition of serial testing of myoglobin with cTnI confirmation to the standard panel did not substantially change the clinical management or outcomes of patients presenting with chest pain and nondiagnostic ECGs.

Adult↗