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Biomedical subjects

R Miller

Publications and source records attributed to R Miller.

At least 505 records · Page 28Linked to original sources
PubMed1991

Hemodynamic and metabolic effects of venoarterial cardiopulmonary support in coronary artery disease.

Coronary angioplasty was performed on 14 high-risk patients supported with venoarterial partial cardiopulmonary bypass. Hemodynamic, metabolic and physiologic parameters were monitored to assess the effect of cardiopulmonary support in conscious patients. Cardiopulmonary support caused a decrease in systolic (45 +/- 17 to 27 +/- 14 mm Hg, p less than 0.001), diastolic (23 +/- 12 to 14 +/- 8 mm Hg, p less than 0.005) and mean (29.7 +/- 13.2 to 18 +/- 9 mm Hg, p less than 0.001) pulmonary artery pressures. Aortic systolic (129 +/- 18 to 106 +/- 17 mm Hg, p less than 0.001), mean (89 +/- 19 to 84 +/- 19 mm Hg, p less than 0.05) and pulse (64 +/- 17 to 37 +/- 16 mm Hg, p less than 0.00001) pressures also decreased. Heart rate and aortic diastolic pressures were unchanged. End-systolic wall stress (122 +/- 48 x 10(3) to 96 +/- 44 x 10(3) dynes/cm2, p less than 0.001) and left ventricular end-diastolic diameter (5.7 +/- 0.8 to 5.5 +/- 0.9 cm, p less than 0.05) were reduced during partial cardiopulmonary bypass. After initiation of cardiopulmonary support, normal lactate extraction across the coronary circulation was diminished or converted to lactate production (38 +/- 23 to 2 +/- 29%, p less than 0.005). There was a marked reduction in hematocrit (41 +/- 4 to 28 +/- 5%, p less than 0.0001) and platelet count (259,000 +/- 57,600/ml to 145,900 +/- 46,000/ml, p less than 0.0001) after bypass. Cardiopulmonary bypass successfully supported all patients during balloon inflation, for an optimal angioplasty result.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Characterization and pharmacokinetic parameters of recombinant soluble interleukin-4 receptor.

The interleukin-4 receptor (IL-4R) is expressed as a 140-Kd membrane glycoprotein that binds IL-4 with high affinity. Recently, cDNA clones for the murine IL-4R have been isolated. One clone encodes an integral membrane protein, while another encodes a protein in which translation is terminated before the transmembrane region, thus producing a soluble form of the IL-4R (sIL-4R). HeLa cell clones overexpressing sIL-4R were isolated using a novel filter-overlay and 125I-IL-4 ligand binding technique. Quantitative analysis demonstrated that the kinetics and affinity of IL-4 binding to the recombinant sIL-4R were similar to the native membrane-bound IL-4R. As low doses of sIL-4R specifically inhibited IL-4-induced proliferative responses in vitro, sIL-4R biodistribution and elimination parameters were evaluated to assess the pharmacokinetic potential of sIL-4R as a therapeutic agent. Pharmacokinetic studies demonstrated that radiolabeled sIL-4R had a distribution half-life of 9 minutes and an elimination half-life of 2.3 hours following intravenous (IV) administration. When administered by intraperitoneal or subcutaneous (SC) injection, the elimination half-lives were prolonged to 4.2 hours and 6.2 hours, respectively. Although the initial blood level of sIL-4R was reduced if administered by SC injection, the bioavailability was comparable with IV administration. The main sites of sIL-4R elimination were the liver and kidney.

Animals↗
PubMed1991

Quantifying non-compliance in patients receiving digoxin--a pharmacokinetic approach.

Non-compliance has a major influence on the successful outcome of a therapeutic regimen. It also unnecessarily increases the costs of health care. In a study involving 137 outpatients receiving digoxin 55 patients (40%) were found to be non-compliant. Patients who experienced communication problems and who lacked a meaningful relationship with their doctor showed a marked deterioration in compliance. An applied pharmacokinetic approach was used to predict the serum digoxin concentration for each patient. The creatinine clearance was determined and the degree of severity of heart failure was assessed. Total body clearance was then calculated. The predicted concentration was also calculated and compared with the measured digoxin concentration enabling an objective assessment of compliance. Twenty-four of the non-compliant patients who had subtherapeutic levels of digoxin (less than 0.8 ng/ml) had signs of cardiac failure. Eighteen of these patients were receiving additional medication (1.7 +/- 0.5 items) for the treatment of cardiac failure.

Digoxin↗
PubMed1991

Anismus in patients with normal and slow transit constipation.

This study examined differences in anorectal function, with particular reference to anismus, which might explain why some patients with intractable constipation have slow and others have normal whole gut transit times. Twenty-four patients were studied; 13 with slow transit (all female, median age 32 years, range 16-52 years) and 11 with normal transit (eight women, three men, median age 37 years, range 21-60 years). Videoproctography with synchronous sphincteric electromyography and anorectal manometry was performed. There were no differences between the two groups, suggesting that slow transit constipation is not secondary to any abnormality in anorectal function and may therefore be a primary disorder of colonic motility. There was no correlation between electromyographic evidence of anismus (pelvic floor contraction on defaecation) and the ability of the patient to evacute the rectum or symptoms of obstructed defaecation. Electromyography findings alone can be misleading and should be related to proctographic evidence of incomplete rectal evacuation before functional anismus can be said to be present.

Adolescent↗
PubMed1991

The sphinctometer: a new device for measurement of lower oesophageal sphincter function.

Current evidence suggests that lower oesophageal sphincter (LOS) competence depends upon both pressure and length. Existing devices can measure length and pressure, but not simultaneously. This methodological problem is a fundamental drawback to understanding LOS function and its role in oesophageal disease. A 'sphinctometer' has been developed, consisting of an oil-filled 3-mm diameter Silastic chamber, 6 cm in length, incorporating a pressure microtransducer designed to provide an integrated pressure reading as a function of length. Its performance has been tested in vitro using human cadaver oesophagus in a specially constructed chamber in which sphincter length and pressure can be varied independently. Comparisons were made with a conventional pull-through technique. Sphinctometer response was linear throughout the LOS pressure range of 0 to 50 mmHg at a fixed LOS length (RS = 0.99; P less than 0.001). Sphinctometer response was also linear at fixed LOS pressure for sphincter lengths from 1 to 6 cm (RS = 0.99; P less than 0.001). This device thus appeared suitable for monitoring function of the human LOS, and has subsequently been successfully incorporated into an ambulatory system for patient use.

Biometry↗
PubMed1991

Intrathecal IgG synthesis and specificity of oligoclonal IgG in patients infected with HIV-1 do not correlate with CNS disease.

The CSF/serum immune response to HIV 1 was studied in 24 patients admitted for investigation. The level of antibody to HIV-1 and specificity of oligoclonal IgG were determined in blood and cerebrospinal fluid (CSF). The majority of patients demonstrated elevated levels of intrathecal IgG synthesis, with levels of HIV-1-specific antibody frequently being significantly higher in CSF than in serum. In 16 of 21 patients the CSF/serum antibody ratio indicated active intrathecal synthesis. Oligoclonal banding was present in CSF from all 24 patients. Immunoprinting of serum and CSF demonstrated antigenic specificity (p24, gp 160, RT) of the clonal antibodies in all of 12 patients though the patterns of reactivity in CSF did not necessarily correspond with that of serum. Although a specific association of particular patterns with HIV CNS disease was not found we feel that these markers should be included in longitudinal studies of HIV-related diseases of the CNS. The specificity of oligoclonal antibodies, both in CSF and in serum was demonstrated, and this specificity may be a useful marker for longitudinal studies in HIV-1 antibody-positive asymptomatic patients.

AIDS Dementia Complex↗
PubMed1991

Two dynamic modes of striatal function under dopaminergic-cholinergic control: simulation and analysis of a model.

A neural network model based on the anatomy and physiology of the matrix compartment of the striatum is described. The model consists of a network of neurons which are mutually inhibitory within a defined domain. A membrane potassium conductance (GK) under dopaminergic-cholinergic control is included in the model. Computer simulation results show that changes in GmaxK can modulate the behaviour of the network to produce either competition or coactivation among striatal output neurons. An analysis of a two-neuron system based on the model shows that the maximum steepness of the threshold function plays a decisive role in the dynamics, in particular with regard to the competition that exists between the neurons. Competitive interactions predominate at low GmaxK, while coactivation predominates at high GmaxK. We suggest that the former dynamic governs reciprocal inhibition of antagonistic muscles, while the latter governs cocontraction and rigidity. The model offers insights into the control of striatal neurodynamics by GmaxK which establish closer links between dopaminergic actions in the striatum and the mechanism of Parkinsonian rigidity. A prediction of the model is that acetylcholine should increase GKmax in striatal output neurons.

Acetylcholine↗
PubMed1991

Rectopexy is an ineffective treatment for obstructed defecation.

The symptoms of obstructed defecation have been attributed to rectal intussusception, and thus rectopexy has been advocated in the surgical management. In this study, patients with obstructed defecation underwent manometry and proctography before and after rectopexy. Seventeen patients (16 females and one male, mean age 51.6 years) were studied. Eleven underwent anterior and posterior fixation of the rectum and six had posterior fixation only. Preoperatively five patients demonstrated rectoanal intussusceptions. Fifteen had significant pelvic descent. No significant change in maximum resting pressure, maximum voluntary contraction, pelvic descent, or anorectal angle was seen postoperatively. In the initial follow-up, many patients had significant amelioration of symptoms. However, on longer follow-up (mean 30.8 months) only two had long-term improvement. The remainder had a poor clinical result in spite of complete resolution of rectal intussusception. Many reported a worsening of symptoms as reflected by an increase in tenesmus and stool frequency. In the two cases with a satisfactory result, both could empty the rectum completely and demonstrated rectoanal intussusception on preoperative evacuation proctography. In those with poor results, four had complete emptying and three had rectoanal intussusception. In conclusion rectopexy is an ineffective treatment for obstructive defecation in most patients.

Adult↗
PubMed1991

Comparison of anterior sphincteroplasty and postanal repair in the treatment of idiopathic fecal incontinence.

Both postanal repair and anterior sphincteroplasty with levatorplasty have been advocated in the treatment of idiopathic fecal incontinence. To assess the functional results of these procedures, physiologic and radiologic measurements were carried out prospectively in 33 patients with idiopathic incontinence undergoing operative treatment, and 12 age- and sex-matched controls. Sixteen patients had anterior sphincteroplasty and levatorplasty and 17 had postanal repair. A satisfactory postoperative outcome was defined as perfect continence or incontinence of flatus only. Ten patients in the anterior sphincteroplasty group had satisfactory results (64 percent) and 10 in the postanal repair group (59 percent). Preoperatively, both groups had decreased resting and squeeze pressures, impaired and mucosal electrosensitivity, and marked pelvic descent vs. controls. Postoperatively, significant improvement in sphincter pressures and mucosal electrosensitivity was seen in both groups. No significant change in anorectal angle was demonstrated in the postanal repair group, whereas it was made significantly more obtuse in the anterior sphincteroplasty group. It is likely that the improved continence resulting from either of these two procedures is secondary to better anal sphincter muscle function and improved and sensation. It would appear that the anorectal angle is not crucial in maintaining continence.

Adult↗
PubMed1991

Mycobacterium haemophilum infection in a patient with AIDS.

We report the isolation of a nutritionally fastidious mycobacterial species, Mycobacterium haemophilum, from the skin of a patient with AIDS. The diagnosis of the mycobacterial nature of the patient's lesions was complicated by extensive Kaposi's sarcoma. It is recommended that slowly growing fastidious mycobacteria be sought in any patients with unusual skin lesions.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Porcine SINEs: characterization and use in species-specific amplification.

A porcine repetitive DNA sequence has been isolated from an intron of the glucose phosphate isomerase gene. The copy number of this and related sequences was estimated to be approximately 10(5) copies per genome. The sequence possesses all the characteristics of short interspersed elements (SINEs) described in other mammals: The repeat is 300 bp in length, has an poly(A)stretch, and contains insertion duplication sites. Homology to seven other porcine sequences, which also have the characteristics of SINEs, has been demonstrated. Primer oligonucleotides, based on conserved regions in the SINE sequences, have been synthesized. Using these primers, PCR-mediated specific amplification of porcine sequences was demonstrated from pig x mouse and pig x hamster hybrid cell lines. Cloning and sequencing of some amplified porcine sequences verify that the sites of priming are SINE sequences.

Animals↗
PubMed1991

Clinical value of pulse oximetry during routine diagnostic and therapeutic endoscopic procedures.

The clinical utility of transcutaneous oxygen saturation monitoring during routine diagnostic and therapeutic esophagogastroduodenoscopy and colonoscopy was assessed in 271 consecutive patients. The mean patient age was 56 years (range 14-86 years). The mean preprocedure oxygen saturation was 94% (range 81-100%). The mean dosages of intravenous meperidine, diazepam and midazolam if administered were 50 mg, 6.4 mg and 3.3 mg, respectively. The largest mean decrease in oxygen saturation of all procedures compared to the preprocedure measurement was 3.2% (p = .0001) and occurred immediately after administration of intravenous medication and endoscope intubation. Colonoscopy and esophagogastroduodenoscopy patients experienced similar decreases in oxygen saturation. The patient's age and sex, type of procedure and physician performing the procedure did not affect the degree of desaturation. The largest mean decrease in oxygen saturation observed was less than that considered normal during sleep. The clinical value of transcutaneous oxygen saturation monitoring in routine diagnostic and therapeutic esophagogastroduodenoscopy and colonoscopy is not supported by the findings of this study.

Adolescent↗