Biomedical subjects
Publications and source records attributed to M Brown.
A case report of a patient known to have long Q-T syndrome (LQTS) undergoing elective oral surgery is presented. While nitrous oxide-narcotic, nitrous oxide-enflurane, or nitrous oxide-halothane techniques for anaesthetic management of LQTS have been previously reported, we report the use of nitrous oxide-isoflurane for the maintenance of anaesthesia. The authors feel that isoflurane is a safe anaesthetic agent for use in LQTS.
Prostaglandin E2 (PGE2) over the concentration range 10(-5)-10(-7) M stimulated calcium uptake in osteoclastic-enriched populations isolated by sequential collagenase digestions of newborn rat calvaria. This effect was on initial calcium uptake occurring at 5 min at 37 degrees C but was not present when isotopic equilibrium was approached (60 min). Prostacyclin (PGI2, PGE1 and PGF2 alpha) stimulated osteoclastic calcium uptake in a similar manner, but with slightly smaller effects than PGE2. Under identical conditions, significant effects of PG were not observed in osteoblastic cells isolated from the same bones by extended collagenase digestions. Combined treatment with PGE2 and parathyroid hormone (PTH) at concentrations which produced no individual effects resulted in a significant increase in calcium uptake in osteoclastic cells. During a 48-h culture period, osteoblastic populations released significantly greater amounts of PGE2 than osteoclastic populations. Pre-incubation for 1 h at 37 degrees C with the prostaglandin cyclo-oxygenase antagonists, indomethacin and flufenamic acid, had no effect on calcium uptake in osteoclastic cells, but resulted in significant decreases in osteoblastic cells. The PGE2-induced increase in calcium uptake on osteoclastic cells was not altered by indomethacin or flufenamic-acid pretreatment. However, after treatment with these inhibitors, a significant response to PGE2 was observed in osteoblastic cells.
The ultrasensitive photochemical silver stain for nucleic acids, described by Beidler et al. (1982), has been applied to the detection of adenovirus restriction fragments as a relatively rapid technique for the identification of virus isolates. In this study, restriction enzyme cleavage analysis was used to characterize adenovirus isolates from what appeared to be two nosocomial outbreaks. The first outbreak was thus shown to include two clusters of patients, and involved two serotypes Ad7c and Ad40. The second outbreak was unrelated and involved Ad35. Although restriction analysis does not replace serum neutralization as a routine method for typing adenoviruses, it is a much more rapid means of discriminating between different patient isolates, providing a current rather than retrospective analysis of a nosocomial outbreak. During the first outbreak, restriction analysis identified two distinct adenovirus serotypes from one patient--Ad7c from a nasopharyngeal aspirate and Ad41 from a stool specimen. Restriction analysis is also valuable for the sub-typing of virus isolates. In this study, the Ad40 and Ad41 isolates were shown to be variants of the respective prototype strains.
During a 13-month period, we studied 148 patients who had percutaneous arterial cannulation for continuous intraoperative, postoperative, and intensive care monitoring. In all patients, alternative arteries were cannulated, which included the brachial (43%), axillary (19%), femoral (28%), dorsalis pedis (8%), and superficial temporal artery (1%). No patient sustained any functionally significant or serious complication requiring surgical intervention. Eighteen patients (12%) had minor, clinically insignificant complications. We conclude that in the absence of an available radial artery, there are at least five other reliable arterial sites that may be cannulated and safely used when direct arterial monitoring is required.
Thirty-five stool specimens, collected over a 14-week period from pediatric gastroenteritis patients and shown to contain adenovirus by electron microscopy, were inoculated onto 293 and HeLa cells. Virus isolates were characterized by serum neutralization and restriction endonuclease cleavage analysis of viral DNA from infected cells. Adenovirus was isolated upon primary inoculation of 293 cells from all 35 specimens shown to contain adenovirus by electron microscopy. Fastidious adenoviruses 40 and 41 (Ad40 and Ad41) were found in 17 (49%) of the stool specimens, and 4 of these specimens contained a conventional species (Ad1, Ad1, Ad18, Ad31) as well as Ad40. This was first manifest by the observation that four of the isolates which initially grew only in 293 cells acquired the capacity to grow in HeLa cells upon subsequent passage. In each case, the conventional species was undetectable by DNA analysis in the original inoculum but was selected in 293 cells and became the only one detectable by the second passage. Four other specimens, containing Ad1 or Ad31 alone, failed to grow initially in HeLa cells but did grow in 293 cells. The results of this study demonstrate therefore that (i) 293 cells are more sensitive than HeLa cells for the isolation of conventional as well as fastidious enteric adenovirus species and (ii) identification of viruses from patient specimens should involve minimal passage of the virus in cell culture, as a single passage can result in misdiagnosis of the virus associated with the infection.
This paper deals with the problem of the controlled closure of excess space in either one or both arches after labial segment alignment or overjet reduction has been achieved. The situations that give rise to the problem are listed. The importance of the need for controlled tooth movement, in order to maintain the antero-posterior labial segment position during space closure, is discussed. A detailed account, with illustrations, of the mechanics involved when using an edgewise system is presented.
Pulmonary artery rupture by a flow-directed balloon-tipped catheter is a rare complication if guidelines for insertion of catheters are strictly applied. It should be stressed that the need for a "confirmed" wedge pressure should be weighed against the very real risk of this potentially fatal complication. Users of this catheter should expect and anticipate distal migration of the catheter tip. Great care must be exercised in inflating the balloon, particularly when the location of the catheter tip in the pulmonary vascular bed is unknown. Excessive catheter manipulation should be avoided. Hemoptysis, hemothorax, cardiac or respiratory instability in patients who have the PA catheter should be suspected to have this grave complication and appropriate emergency measures should be taken until this complication has been ruled out.
Disturbances of potassium, calcium, phosphate and magnesium homeostasis in diabetes mellitus are well documented. We have compared the effects of semisynthetic human and pancreatic porcine insulin on transmembrane shifts of these ions, and on glucose metabolism, at two insulin infusion rates, 20 and 50 mU/kg/h, during euglycaemic clamping for 2 h in 6 normal volunteers. The glucose requirements and the changes in blood metabolite concentrations were not significantly different during the porcine and human insulin infusions. Serum potassium levels, however, showed a significant greater decline with infusions of porcine insulin (4.2 +/- 0.1 to 3.5 +/- 0.1 mmol/l) compared with human insulin (4.2 +/- 0.1 to 3.7 +/- 0.1 mmol/l) at 50 mU/kg/h (P less than 0.05). Potassium levels were significantly lower during the porcine insulin infusion at 105 and 120 min and at 15 and 30 min after stopping the infusion. Electrocardiographic T-wave voltage decreased during the porcine and human insulin infusion by 0.13 +/- 0.02 and 0.10 +/- 0.01 mV, respectively (P less than 0.02). Changes in serum levels of magnesium, calcium, phosphate, and red blood cell concentrations of magnesium and 2,3-DPG, were not significantly different between the insulins. Thus a small but significant greater decline in potassium levels with similar glucose requirements was found during iv administration of porcine insulin compared with human insulin.
Health care financing has undergone numerous structural changes over the years. Change continues while extreme growth seriously affects the health care focus. The author examines the multiclass system and health financing trends. Restructuring techniques are also discussed.
A patient with sarcoidosis developed bilateral bronchopleural fistulae and was managed with high-frequency ventilation. A review of this technique along with other mechanical ventilatory measures is presented.
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The anti-phosphocholine (PC) memory response elicited in BALB/c mice by phosphocholine-keyhole limpet hemocyanin (PC-KLH) contains two groups of antibodies distinguished by their fine specificity for PC and p-nitrophenylphosphocholine (NPPC). Group I antibodies are inhibited by both PC and NPPC, while Group II antibodies are inhibited appreciably only by NPPC; only Group I antibodies are dominated by the T15 idiotype. Anti-PC hybridomas representative of the memory response to PC-KLH were produced to examine the variable region genes expressed by memory B cells. Two IgM hybridomas were of the Group I type, because they were inhibited by both PC and NPPC and they bound to the pneumococcus R36A. However, only one of these antibodies (PCM-2) expressed a T15 idiotope, while the other (PCM-1) did not express any of three T15 idiotopes. Despite its negative T15 idiotype profile, N-terminal amino acid sequencing of PCM-1 purified heavy chain and Southern blots of the hybridoma DNA indicated that it utilizes the T15 VH and JH1 genes. Three hybridomas, IgG1, IgM, and IgE, typical of Group II antibodies, were examined; these were negative for three T15 idiotopes and displayed measurable avidity only for NPPC in a PC-protein binding inhibition assay. These three hybridoma antibodies, like serum Group II IgG1, did not measurably bind to the bacterium R36A. The heavy chain amino termini of all three of these antibodies were inaccessible for Edman degradation. Southern blots of DNA from the IgG1 hybridoma revealed the T15 VH gene to be in the germ line configuration only and unassociated with any JH segment, indicating that this Group II antibody utilizes a VH gene different from the T15 family. These results signify that, whereas some diversity of the (anti-PC) memory response may be generated by somatic diversification of variable regions important in the primary response, a significant contribution to the overall heterogeneity of memory antibodies originates in the expression of additional variable region genes.
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We investigated the heterogeneity of anti-phosphocholine (PC) antibodies present in human serum taken from individuals before and after immunization with a multivalent pneumococcal vaccine. The fine specificity of IgM, IgG, and IgA anti-PC antibodies was determined in an ELISA by using phosphocholine or p-nitrophenyl phosphocholine (NPPC) to inhibit binding of antibody to PC-histone. We identified two populations specific for PC that differed in their binding properties. One population is inhibited by NPPC much better than by PC and is most evident in IgG antibodies. The second population has similar avidity for PC and NPPC and is consistently associated with the IgM and IgA isotypes as well as with IgG. The IgG antibodies in both populations were predominantly of the IgG2 subclass. Both populations were found in serum samples taken before immunization with pneumococcal vaccine, suggesting that they had been stimulated through prior environmental contacts with PC-containing antigens. Previously, we found populations with similar fine specificity patterns in the murine response to PC. The two murine antibody populations have been shown to derive from different immunoglobulin variable region genes. The presence of comparable antibody populations in the human suggests the possibility that these two fine specificity families have been conserved in evolution.
Intracisternal injection of ovine corticotropin-releasing factor (CRF) into the pylorus-ligated rat or the rat with gastric fistula resulted in a dose-dependent inhibition of gastric secretion stimulated with pentagastrin or thyrotropin-releasing hormone. When injected into the lateral hypothalamus--but not when injected into the cerebral cortex--CRF suppressed pentagastrin-stimulated acid secretion. The inhibitory effect of CRF was blocked by vagotomy and adrenalectomy but not by hypophysectomy or naloxone treatment. These results indicate that CRF acts within the brain to inhibit gastric acid secretion through vagal and adrenal mechanisms and not through hypophysiotropic effects.
An in vitro culture system is described in which antibody synthesis is initiated by 10(5) hapten-primed spleen cells in 20 microliters hanging drops. Plaque-forming cell (PFC) responses to thymus dependent and thymus independent antigens were obtained in drop cultures comparable to the micro Mishell--Dutton system. Antigens could be administered in soluble form or on antigen-pulsed peritoneal cells. The hanging drop method also provides a reliable yet simple procedure for cloning hybridoma cells while permitting direct visualization of the number of cells in each drop.
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The binding of prostaglandin E2 (PGE2) to bone cells was studied to provide direct evidence for the existence of specific receptors in bone. Bone cells were isolated by collagenase digestion of fetal and newborn rat calvaria. Isolated cells were incubated with 3H-PGE2 and collected on Millipore filters. Specific binding was determined by subtracting the binding that occurred with 10(-6) M non-radioactive PGE2 and 3H-PGE2 from that with 3H-PGE2 alone. With heterogeneous cell preparations and at PGE2 concentrations from 10(-9) - 1.7 X 10(-8) M at 37 degrees C, specific binding reached steady state within 10 min. Bound 3H-PGE2 was displaced by the addition of increasing amounts of unlabeled PGE2. Inhibition of PGE2 binding was observed with PGE1 and the endoperoxide analog, U44069, but not with PGF2 alpha, a lipopolysaccharide, or 13,14-dihydro 15-keto PGE2. Studies with bone cell populations, obtained by sequential digestions, indicated that an osteoclastic population binds 30-fold more PGE2 than osteoblastic cells. Scatchard analyses revealed that the osteoclastic cells have an affinity constant for PGE2 binding similar to that obtained with heterogeneous populations. However, the PGE2 binding capacity in this osteoclastic population was fivefold greater than in the heterogeneous population. The osteoclastic population responded with an increase in cyclic AMP to lower concentrations of PGE2 than the osteoblastic populations. These studies suggest that differences in the binding capacity of PGE2 receptors exist among bone cell-types and that these differences are reflected in the cellular cyclic AMP response.