Biomedical subjects
Publications and source records attributed to A C Brown.
We describe a patient who presented with a history of unexplained exertional dyspnea and pulmonary infiltrates. She was evaluated for interstitial lung disease, presumed to be idiopathic and underwent an open lung biopsy. The pathologic findings were compatible with exogenous lipoid pneumonia and her history revealed longstanding use of intranasal petroleum jelly (Vaseline) at bedtime.
A PCR-based method is described for the production of cDNA libraries and total cDNA probes from a few milligrams of tissue. Using a model system, we show how a PCR library and PCR probes can be used to identify genes expressed at different levels in two tissues. Small amounts of tissue derived from two plants, one infected with arabis mosaic virus and the other uninfected, were used to make a library and probes. This library and the probes were used to identify viral genes expressed only in the infected plant.
The purpose of this study was to examine the effect of dietary cholesterol on the total blood cholesterol levels of nondiabetic and streptozotocin-diabetic rats. Thirty-six Sprague-Dawley rats were divided into four groups: nondiabetic/control diet (C), streptozotocin-diabetic/control diet (D), nondiabetic/control diet + 2% cholesterol (CH), and streptozotocin-diabetic/control diet + 2% cholesterol (DH). Plasma cholesterol levels were not significantly elevated in the D group (63.4 +/- 9.0 mg/dl) when compared with the C group (71.3 +/- 3.9 mg/dl) but were significantly higher (p < 0.01) in the CH group (89.8 +/- 8.1 mg/dl). There was nearly a six-fold significant elevation (p < 0.0025) in the DH group (530.0 +/- 58.0 mg/dl) contrasted to the nondiabetic rats fed the same diet. The results of this study indicate that streptozotocin-diabetic rats fed a high cholesterol diet experience hypercholesterolemia.
Between 1971 and 1991, 41 patients underwent anterior resection for the treatment of complete rectal prolapse. Anterior resection was performed after full rectal mobilization to the levator ani muscles with reanastomosis (39 hand-sewn and two stapled) carried out to peritonealized distal rectum. The 41 patients comprised 35 women and six men with an average age of 56 years (range, 7-88 years). Postoperative follow-up averaged 6 years (range, 6 months to 18 years). Three patients (7%) suffered recurrent prolapse in 2, 2.5, and 5.5 years, respectively. Mortality was 0 per cent; morbidity was 15 per cent including three incisional herniae, two small bowel obstructions, and one stroke. No pelvic sepsis, abscess, or anastomotic dehiscence occurred. Anal incontinence was a preoperative finding in 21 patients (51%) with rectal prolapse. Nineteen of these patients (90%) noted either improvement or no change in postoperative continence. Anterior resection is a familiar, frequently performed operation that does not require a foreign body or rectal suspension. We believe this to be the procedure of choice for patients with complete rectal prolapse. Anterior resection withstands long-term scrutiny both in terms of recurrence rate and associated complications.
Eleven diurnally active asthma patients having a history of nocturnal asthma and treated regularly with albuterol or metaproterenol alone or with twice-daily sustained-release theophylline were evaluated for day-night pattern in peak expiratory flow (PEF) and use of supplemental beta-agonist aerosol for relief of acute asthma. Overall, significant day-night variation was observed in the supplemental use of beta-agonist medication and in airway patency. The patients managed by albuterol or metaproterenol alone used supplemental beta-agonist medication significantly more between 4 AM and 8 AM and also 8 PM and midnight in comparison to 4 PM to 8 PM; this was not true for those treated with both theophylline and beta-agonist aerosol. In patients taking a beta-agonist bronchodilator, the 24-hour mean PEF was greater than in those who also took theophylline, but the day-night variation in PEF was comparable. Supplemental isoproterenol use was significantly correlated with circadian amplitude of the PEF rhythm, but not with the 24-hour mean PEF. The greater the day-night variation in PEF, the greater the reliance on a supplemental beta-agonist bronchodilator.
In situ hybridization and Northern analysis of heme oxygenase (HO) mRNA was used to determine the induction and expression of HO by various environmental agents. Exposure of Hep3B cells to hemin (10 microM) for as little as 5 min resulted in significant production of HO transcripts and mRNA expression as seen by in situ hybridization. We followed the pattern of HO transcript accumulation by heme and results indicate that the peak of induction of HO by heme was reached between 10 and 20 minutes. Other metalloporphyrins were all effective in inducing HO mRNA after 1 h exposure. On the other hand, CoCl2 caused accumulation of HO mRNA at a later time than seen with the metalloporphyrins. However, lipopolysaccharide (LPS) gave a more immediate effect on HO induction which was somewhat similar to heme in its time course. Direct measurements of HO activity revealed that enzyme activity could be detected after about 20 min exposure to hemin, and this activity was inhibited by tin protoporphyrin (SnPP). The different pattern of HO mRNA induction by LPS as contrasted with CoCl2 suggests that LPS may act through a different translational factor, or stimulate free radical formation and the subsequent release of heme and induction of HO. These results indicate that heme causes accumulation of HO mRNA by a different mechanism than that of CoCl2. Finally, LPS shares a concomitant effect on induction of HO as an acute phase reactant type protein.
The effect of two beta 2-adrenoceptor agonists, salbutamol (100 micrograms/kg i.v.) and broxaterol (100 micrograms/kg i.v.), on airway microvascular leakage induced by vagal stimulation was studied in anaesthetised guinea pigs. Airway microvascular leakage was measured by Evans blue extravasation. Broxaterol, but not salbutamol, inhibited Evans blue dye extravasation at all airway levels, an effect prevented by pretreatment with propranolol (1 mg/kg). Neither of the beta 2-agonists had any effect on substance P-induced Evans blue dye extravasation. Broxaterol inhibits the prejunctional release of tachykinins from airway sensory nerves by stimulation of beta-receptors. The mechanism by which beta-adrenoceptor agonists prevent airway microvascular leakage deserves further study.
APIS is a software package based on mathematical modelling which provides a reliable approach in optimizing drug therapy. It was designed to assist clinicians in interpreting blood drug levels so that drug therapy may be better and more cost-effective. It is a methodological approach to describe, predict and control the kinetic behaviour of a drug. This software incorporates the principle of Bayesian procedures, i.e. one can use all available patient information (population) to determine patient-specific parameter estimates. These estimates can then be used to design an optimal and individualized drug regimen. APIS is an attractive and useful tool for clinical and experimental pharmacokinetics. APIS may be used on any IBM compatible computer using the Microsoft-Windows environment. The software is menu driven to provide a very user-friendly tool for analysing pharmacokinetic data and for designing dosage regimens.
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Body Mass Index (BMI) was calculated from self-reported height and weight for 1,123 university students who returned a questionnaire mailed to a 10 percent random sample of the entire undergraduate population of a large midwestern university. Seventeen percent of the females and 20 percent of the males were determined to be in excess of normal BMI standards. However, significantly more women (40%) considered themselves overweight in comparison to men (24%). Also, significantly more women (53%) than men (20%) reported experiencing discomfort due to excessive weight. Inaccurate perceptions of body image are common among individuals with eating disorders. There is a higher incidence of eating disorders among college-age women than among their male peers. A distorted body image as reflected by perceived overweight may serve as a marker for individuals at risk for eating disorders.
The purpose of this study was to provide descriptive information on migrant farm laborers' infant feeding practices in northern Colorado. We used a survey questionnaire to interview 49 families with a 6- to 23-month-old child who was enrolled in the Migrant Head Start Center. Sixteen (33%) of the mothers breast-fed their infants, but only five (14%) of the 35 Mexican Americans breast-fed. Thirty-four (69%) of the mothers used formula and seven (14%) gave their child cow's milk at birth. Introduction of solids occurred at a mean of 6.6 months. Of the respondents, 13 (27%) introduced solids before 4 months of age, whereas 29 (59%) introduced solids before the age of 6 months. Thirty-six (73%) of the migrants put their child to bed with a sweetened beverage, milk, or formula in a bottle. Diarrhea in the children was reported by 39 (80%) of the migrants, with 15 (31%) stating that it occurred at least once per month. One third (n = 16) of the respondents reported that their children had constipation lasting 1 to 14 days, but for most (n = 10) it occurred less than once per month. Results suggest that migrant families need more dietary recommendations about breast-feeding, introduction of liquids/solid foods, proper formula preparation, avoidance of baby bottle tooth decay, and treatment of diarrhea and constipation.
Stepfamilies in therapy for a child-focused problem were compared to those without such a problem and not in therapy. Differences were found in reciprocity within the stepparent-stepchild relationship, satisfaction with the stepparent's role, level of stepfamily conflict, and degree of stepfamily expressiveness. Results are discussed in terms of current research and clinical implications.
Twenty-three diurnally active (0705-2333), healthy persons between 22 and 54 years of age and without history of sleep abnormality were monitored continuously for 120 consecutive hr (five days) by wrist actigraphy. Circadian rhythms of high amplitude were detected by cosinor analysis for each participant and for the groups of 10 males and 13 females with the average span of heightened activity timed between approximately 1330 and 1605. The circadian peak-trough difference in wrist movement was marked, equalling approximately 75% of the 24-hr mean level. In 19 of 23 participants, the 24-hr mean of wrist activity varied between 140-180 movements/min, with four persons exhibiting lesser means of 110-140 movements/min. With respect to the daytime span of activity, the mean wrist movement of individual participants ranged from 155-265 movements/min, with the majority (20/23) varying between 185-245 movements/min. During nocturnal sleep the mean wrist activity level was quite low, varying between individuals from 5 to 25 movements/min for 21 of 23 persons. Wrist actigraphy proved to be well-accepted and was a most reliable means of monitoring aspects of body movement during activity and sleep in ambulatory persons adhering to usual life habits and pursuits.
Patients with difficult airways present a challenge when they must undergo anesthesia. This article examines the problems inherent in evaluating patients with difficult airways for surgery. The authors believe that these patients are best evaluated in a Difficult Airway Clinic. The structure and organization of such clinics are examined.
Concern has been expressed over the use of the halogenated anaesthetics halothane (CF3CClBrH), enflurane (CF2HOCF2CFClH) and isoflurane (CF2HOCHClCF3) because of their potential for stratospheric ozone destruction. Halogenated species also contribute to global warming. The significance of the anaesthetics in stratospheric ozone loss or in 'greenhouse' heating depends on their atmospheric lifetimes. Because reaction with hydroxyl (OH) radicals is likely to be the main homogeneous sink for these species in the troposphere, we have measured absolute rates of reaction with OH. Comparison with a one-dimensional model indicates that the lifetimes of halothane, enflurane and isoflurane with respect to this reaction are 2, 6 and 5 years, respectively. Thus the small production of the anaesthetics is not offset by anomalously long atmospheric lifetimes to give a large atmospheric burden of the compounds. The anaesthetics will contribute at most a fraction of approximately 5 x 10(-4) to the total atmospheric content of chlorine-containing species.
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A prospective study of 18 consecutive patients undergoing unilateral, partial-thickness, distal, internal sphincterotomy for the treatment of chronic anal fissure was performed. Biopsies were taken from the base of the fissure and from the lateral muscle before division. Normal specimens were taken from the internal anal sphincter of patients undergoing abdominoperineal resection. Specimens confirmed the presence of fibrosis throughout the internal anal sphincter in patients with anal fissures, but none in controls.
The purpose of this work was to measure the permeability (hydraulic conductance) of root canal apical barriers in vitro. In 30 extracted teeth, the pulp tissue was removed and the apical opening standardized and enlarged using endodontic files. One-millimeter thick barriers of either autogenous dentin chips, calcium hydroxide powder, or durapatite particles were placed just inside the apical opening. The prepared teeth were mounted in a special chamber, fluid pressure applied, and the resultant flow measured. The permeability of dentin chip barriers in 10 additional teeth with nonstandardized apical openings was measured also. The standardized canals with the autogenous dentin chip barriers had a mean permeability of 0.0010 microliter/s/psi at 20 psi applied pressure. Teeth with calcium hydroxide barriers averaged 0.0012 microliter/s/psi. The durapatite particle barriers were much more permeable and averaged 0.0220 microliter/s/psi. It was concluded that this technique is useful in evaluating the effectiveness of apical barrier materials. For the materials tested, autogenous dentin chips and calcium hydroxide barriers have significantly lower permeability than durapatite barriers (p = 0.05).