Biomedical subjects
Publications and source records attributed to J Brown.
With the refinements in the Sphincter 800, better patient selection and improved surgical techniques, the artificial urinary sphincter now offers a viable treatment alternative in the management of urinary incontinence arising from sphincteric incompetence.
In a trial to test the immunogenicity and the safety of a rabies human diploid vaccine it was found that the geometric mean titre (GMT) of individuals immunized with other rabies vaccines within two years of the trial was statistically significantly smaller than the GMT of individuals immunized with other rabies vaccines more than two years prior to the trial (Scheffé test, 5% level of probability). Since this result was unexpected, an unplanned analysis of the data was undertaken. Rapid fluorescent focus inhibition titres are expressed as international units per milliliter of serum (IU/ml). The IU/ml titres, based upon logarithmic calculations, are a coarse arithmetic measurement. A proposed index system for these titres smooths out this coarseness and permits meaningful statistical comparisons.
The diagnosis of multiple gestation at the time of genetic amniocentesis is a routine occurrence. In a combined series of 2765 patients referred for antenatal genetic studies from the Medical College of Virginia and the University of Iowa, 34 twin pregnancies were encountered (1.2%). Twenty-six of the patients with twins were referred for advanced maternal age. The other indications were previous neural tube defects (1), previous trisomy 21 (2), known carriers of Tay Sachs disease (2), previous Turner's syndrome (1), family history of trisomy 21 (1), and one pregnancy was referred because of an abnormal ultrasound. Amniocentesis procedures, outcome of the twin pregnancies, and genetic counseling issues, are discussed.
We studied 117 inferior vena cava (IVC) replacements in dogs to determine the effects of graft material, graft size, endothelial seeding, and cultured endothelial linings on graft patency. As a control, the IVC was removed and reimplanted in 11 dogs. Dacron (n = 7) and expanded polytetrafluoroethylene (e-PTFE) grafts (n = 12) were seeded immediately with the use of enzymatically derived autogenous jugular vein endothelium. Cultured linings were prepared for e-PTFE grafts (n = 9) by inoculating the graft with jugular endothelium and nurturing the lining in tissue culture for 14 to 30 days before implantation. Unseeded grafts (n = 27) were prepared according to the manufacturer's recommendations. These six methods of preparation were tested in grafts measuring 6 mm I.D. and 60 mm in length. Other sizes were tested with a Latin square study design. After 30 to 60 days the grafts were perfusion fixed and studied with light and transmission electron microscopy. Patency was determined by contrast cavography after 7 and 30 days. Patency in the IVC reimplantation was 100% compared with 28.0% of the e-PTFE (p = 0.001) and none of the Dacron grafts that measured 6 mm I.D. and 60 mm long. e-PTFE and Dacron graft patency also differed significantly (p = 0.035). Seeded and culture-lined e-PTFE grafts in that same size were patent in 31.6% compared with 16.7% of unseeded e-PTFE. With grafts measuring 80 mm long, three of the five e-PTFE grafts were patent between 3 and 7 days. All progressed to occlusion by 30 days and compared poorly with all other graft sizes tested (2.6% progression to occlusion [p = 3 X 10(-8)]). Recanalization was not seen in 10 occluded grafts that were followed for 60 days. The histologic features of seeded grafts differed remarkably from grafts previously studied in the arterial circulation and from culture-lined and unseeded venous prostheses in that 60% had prominent large, random, endothelium-lined channels within the inner capsule. Larger graft diameters (p = 0.009) and the omission of an endothelial surface treatment (p = 0.004) were associated with anastomotic subendothelial fibrous hyperplasia. We conclude that graft material is the major determinant of patency in IVC replacements, that an extensive endothelial surface promotes patency, but that simply seeding e-PTFE or Dacron grafts with 10(5) endothelial cells does not provide sufficient endothelium to alter early patency.(ABSTRACT TRUNCATED AT 400 WORDS)
Iron (Fe2+) and gadolinium (Gd3+) chelated to ethylenediaminetetraacetic acid and Gd3+ chelated to diethylenetriamine pentaacetic acid have been used as contrast agents in nuclear magnetic resonance imaging of the normal kidney and cerebral infarction in rabbits. All three agents produced observable changes with inversion-recovery images and marked changes in T1.
The genetically defined miniature pig developed by Sachs et al. was selected as a large animal model to test the feasibility of fetal pancreas transplants for reversal of insulin-dependent diabetes. In order to test our approach, the first key was to characterize the development of the pig pancreas tissues throughout fetal life. Pancreas samples were obtained from 102 farm pig fetuses ranging in age from 35-110 days and from 39 minipig fetuses removed by Caesarean section from 5 timed-pregnant sows between 33 and 73 days after conception. The development of the endocrine and exocrine pancreases were examined by immunobiochemical assays of insulin, chymotrypsinogen, and trypsinogen. Light and electron microscopic examination of pancreases from the critical fetal ages (35-55 days) were used to confirm the above results. Insulin was already present at day 33 and increased rapidly till birth (day 114: 2.2 U/pancreas). Chymotrypsinogen activity was first detected at day 43 and trypsinogen activity at days 49-50. Enzyme content increased rapidly till days 65-70 and then more gradually until birth. Morphological development of exocrine cell granules conformed to the above results. The results clearly demonstrated in the pancreas of a larger mammal, the pig, that the endocrine elements mature prior to the exocrine system. Thus, as we found in rats, pig fetal pancreas also has this advantage as a donor tissue for transplantation. An appropriate fetal age for pig donors is estimated to be between 45 and 50 days.
The effects of two single oral doses of ibopamine (150 and 600 mg) on heart rate, blood pressure, urine flow, sodium, potassium and creatinine excretion were studied in normal volunteers. No significant change was observed in urine flow, sodium, potassium or creatinine excretion at either dose. No significant change was observed in heart rate or blood pressure except that systolic blood pressure was transiently elevated after the 600 mg dose (P less than 0.05).
In a consecutive series of 1,067 patients entered into the data base of the Melanoma Cooperative Group at New York University School of Medicine between 1972 and 1980, 120 men were of draft age (18-31 years) during World War II (1941-1945). Questionnaires were sent to these 120 individuals; 89 responded. Simultaneously, a control (nonmelanoma) population of 65 men of similar age was queried. Each subject in both groups was asked whether he had served in the armed forces during World War II and, if so, what were his theaters of operation. Based on the response, 83% (74 of 89) of the melanoma group compared with 76% (49 of 65) of the control group had served in the armed forces during World War II; however, a significantly (p = 0.0002) greater percent of the melanoma patients (34%) served in the tropics than did the control subjects (6%). Further, overrepresented in the melanoma group that served in the tropics (compared with the melanoma group who served in the armed forces in nontropical theaters) were malignant melanomas that had their origin in nevocytic nevi. The findings suggest that Caucasian individuals heavily exposed to sunlight in the tropics for several years during early life may be at higher risk to the subsequent development of cutaneous malignant melanoma. In some individuals this may be a two-step phenomenon, in which the first step is the solar induction of nevocytic nevi and the second is malignant transformation within them.
Cysteamine (beta-mercaptoethylamine HCl) (1.0-40.0 mM) induced a concentration-dependent increase in tonic and phasic contractions of segments of guinea-pig ileum in vitro. Myenteric plexus-longitudinal muscle (MPLM) preparations also responded with an increase in tonic contractions but phasic contractions were either greatly reduced or absent, indicating that these were a response of the circular muscle. Atropine (5 microM) inhibited the cysteamine-induced contractions, whereas hexamethonium and guanethidine had no effect, suggesting that cysteamine was acting at least partly via a cholinergic mechanism involving muscarinic receptors. Tetrodotoxin increased the phasic contractions of ileal segments, but had no effect on the tonic component. Treatment of MPLM preparations with morphine (1 microM) resulted in a small reduction in responsiveness to cysteamine, and blocked electrically-induced contractions by at least 90%. Since morphine acts by inhibiting acetylcholine release via hyperpolarization of intrinsic neurones, a small but significant part of the cysteamine-induced contractions probably resulted from stimulation of acetylcholine release from intrinsic neurones. Following a response to high cysteamine concentrations (greater than 15 mM) tissues were refractory to subsequent cysteamine administration. Cross-desensitization between cysteamine and acetylcholine also occurred, as short-term (1-3 min) incubation of MPLM preparations with high concentrations of either compound (1-10 microM acetylcholine or 20 mM cysteamine) resulted in a reduced responsiveness to both. A reduced sensitivity to acetylcholine or cysteamine was obtained following long-term (45 min) incubation with acetylcholine (1 microM). Removal of Na+ from the incubation medium negated this effect. In contrast, the refractoriness to acetylcholine or cysteamine following long-term (45 min) incubation with cysteamine (20 mM) was accentuated in low Na+ medium. It is suggested that cysteamine induces a contraction of both the circular and longitudinal muscle of the guinea-pig ileum by stimulating the release of acetylcholine from intrinsic neurones, by an action at the level of the smooth muscle muscarinic receptor, and possibly by a non-cholinergic mechanism. However, the mechanisms by which acetylcholine and cysteamine induce tissue refractoriness probably differ.
A microcomputer algorithm for tachycardia identification, suitable for use in an implanted antitachycardia pacemaker, is described. The system employs an atrial and ventricular electrogram, detects a sustained fast rate in either chamber, and awakens the main program to perform detailed analysis of the tachycardia and its immediately preceding beats. The algorithm distinguishes atrial, ventricular, and AV nodal and re-entrant tachycardia from high rates due to sinus tachycardia. For testing of the program, we used a data base of twenty-two tape-recorded and documented arrhythmias provoked during electrophysiologic studies in which atrial and ventricular bipolar electrodes were in place; twenty-one were successfully detected. These included atrial fibrillation, atrial flutter, atrial tachycardia, AV nodal re-entrant tachycardia, AV re-entrant tachycardia using an accessory pathway, and ventricular tachycardia with and without ventriculo-atrial conduction.
We have developed a microcomputer algorithm for tachycardia identification suitable for use in an implanted antitachycardia pacemaker. The algorithm distinguishes atrial, ventricular, and AV reentrant tachycardia, while ignoring high rates due to sinus tachycardia. A new method whereby the pacemaker delivers an atrial extrastimulus has been developed for distinguishing paroxysmal 1:1 tachycardia from sinus tachycardia, and has undergone preliminary testing in the electrophysiology laboratory. Preliminary results indicate sinus tachycardia can be reliably distinguished from paroxysmal 1:1 tachycardia by a properly timed extrastimulus delivered to the right atrium.
Antihypertensive treatment may be life saving in scleroderma renal crisis. Patients surviving such crises frequently have had dramatic improvement in the dermal manifestations of their scleroderma. To investigate the potential role of antihypertensive treatment in nonhypertensive patients we randomly assigned 28 patients with systemic sclerosis into drug (14) and placebo (14) groups, using blocked randomisation , and followed them up in a prospective, double-blind clinical trial for 24 months. Overall, both groups improved slightly, with both subjective and objective markers. There were no statistically significant differences and no clinically meaningful trends between the 2 groups, except that the blood pressure was reduced in the group on the active drug.
Explore the source record for details and available documents.
We sought to correlate the inhibin activity of individual ovarian follicles (greater than 16 mm in diameter) from untreated (7 patients; 7 follicles), clomiphene-stimulated (150 mg/day; menstrual cycle days 5-9; 9 patients, 14 follicles), and human menopausal gonadotropin (hMG)-stimulated (150 IU/day; menstrual cycle days 3-11; 8 patients; 23 follicles) ovarian cycles and to correlate these results with the follicular fluid (FF) steroid concentration. Follicular aspirates were obtained via laparoscopy from 24 regularly menstruating patients when the diameter of the largest follicle reached 20 mm, as determined by serial ultrasonography. FF concentrations of estradiol, progesterone, testosterone, 17-hydroxyprogesterone, and androstenedione were determined by RIA. Inhibin activity was determined using the inhibition of basal 24-h FSH secretion by dispersed rat anterior pituitary cells. Inhibin values were highest among the follicles aspirated from those patients who received hMG [277 +/- 31 (+/- SE) U/ml] compared to untreated subjects (51 +/- 13 U/ml) or those who received clomiphene (96 +/- 14 U/ml). Estradiol was highest in FF from untreated patients (2295 +/- 1155 ng/ml) compared to levels in patients who received hMG (368 +/- 1.76 micrograms/ml) or clomiphene (1049 +/- 174 ng/ml). FF progesterone values were highest in untreated patients (9.4 +/- 2.59 micrograms/ml) compared to those in hMG-treated (5.04 +/- 1.76 micrograms/ml) and clomiphene-treated patients (7.82 +/- 1.24 ng/ml). FF 17-hydroxyprogesterone values (7.82 +/- 1.24 ng/ml). FF 17-hydroxyprogesterone values were similarly higher in the untreated (1.55 +/- 0.21 micrograms/ml) and clomiphene-treated (2.54 +/- 0.27 micrograms/ml) patients than in the hMG-treated group (0.73 +/- 0.09 micrograms/ml). FF androstenedione (untreated, 50.7 +/- 30 ng/ml; clomiphene-treated, 73.4 +/- 23.4 ng/ml; hMG-treated, 60.2 +/- 19.8 ng/ml) and testosterone (6.66 +/- 2.45, 5.98 +/- 1.46, and 6.39 +/- 2.16 ng/ml, respectively) concentrations in all three patient groups were similar. In untreated patients, there was a highly significant positive correlation between intrafollicular inhibin activity and FF estradiol, testosterone, and androstenedione concentrations and a statistically significant negative correlation between intrafollicular inhibin activity and FF progesterone concentrations. Patients receiving clomiphene therapy demonstrated at least two different response patterns, one with a positive and one a negative correlation between intrafollicular inhibin activity and FF steroid concentrations. The patients receiving hMG therapy had no statistically significant correlation between intrafollicular inhibin
Eight whole-night polysomnographic recordings were conducted in a 33-year-old man with a localized pontine lesion inflicted by a shrapnel fragment. Sleep recordings revealed no rapid eye movement (REM) sleep in 3 nights, and markedly reduced REM sleep in 5 nights; non-rapid eye movement (NREM) sleep was normal. In spite of marked reduction of REM sleep, the patient conducted a normal life and had none of the typical symptoms of REM-sleep deprivation.
Magnetic resonance imaging (MRI) was performed in 20 patients before and after intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) in a dose of 0.1 mmol/kg. Twelve of the patients had clinical and histologic diagnoses of cerebral tumor, six had hepatic tumors, one had hepatic cysts, and one had transitional cell carcinoma of the bladder. Contrast enhancement was seen with all tumors, but not with the hepatic cysts. The degree of enhancement was greater than that seen with computed tomography (CT) in 13 cases, equal to it in six, and less in one. Contrast enhancement was detectable as long as 18 hr after injection of Gd-DTPA in one case of cerebral tumor. The margin between cerebral tumor and peritumoral edema could be delineated with contrast-enhanced MRI to the degree possible with contrast-enhanced CT. In the liver isointense enhancement was seen with saturation-recovery (SR), inversion-recovery (IR), and spin-echo (SE) sequences although not with all three sequences simultaneously. In general IR sequences were most sensitive for display of the contrast agent, but the enhancement often decreased the difference between abnormal and normal tissue. No short-term side effects were encountered and no significant change was seen in urea, creatinine, electrolytes, liver function tests, blood coagulation, or urine testing after injection of Gd-DTPA. Although much more work will be required to evaluate this contrast agent, these initial experiences are very promising.
A dengue 4 (strain H241, PDK35-TD3 FRhL p3) vaccine attenuated by passage in primary dog kidney cells followed by passage and final vaccine preparation in DBS-FRhL-2 cells was tested in five yellow fever-immune volunteers. Only two volunteers seroconverted by producing hemagglutination-inhibiting and neutralizing antibodies. Mild illness, compatible with dengue infection was found only in the individuals who later developed antibodies. Both volunteers developed a rash by the 8th day following vaccination, coinciding with a slight elevation in temperature and leukopenia. Additionally, several serum enzymes were elevated during the observation period. Dengue 4 virus was isolated from the blood of the two infected volunteers starting as early as day 5 post vaccination. During the viremic period, which lasted 5 days, phenotypically-changed virus was recovered, indicating genetic instability of the vaccine virus. The clinical disease and immune response in the two infected individuals was probably related to replication of the variant virus. Further testing of this vaccine in its present form is not indicated.
Explore the source record for details and available documents.