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Biomedical subjects

R Davis

Publications and source records attributed to R Davis.

At least 325 records · Page 18Linked to original sources
PubMed1990

Brief group psychoeducation for bulimia nervosa: assessing the clinical significance of change.

Forty-one women with bulimia nervosa completed a brief intervention that was designed to promote symptom management. Cutoff scores for the determination of reliable and clinically significant change were calculated for several psychometric instruments that are commonly used as outcome measures in the field of eating disorders. Using these statistical procedures to assess therapeutic change, this study documents the diversity of outcomes that individuals reported following their participation in the intervention. As expected, there was a differential reporting of clinically significant change in favor of specific eating psychopathology relative to personality features and associated psychopathology.

Adult↗
PubMed1990

MyoD binds cooperatively to two sites in a target enhancer sequence: occupancy of two sites is required for activation.

MyoD is a master regulatory gene for myogenesis. Its product, the MyoD protein, appears to act by binding to muscle-specific enhancer sequences. We show that MyoD binds cooperatively to two sites in the muscle-specific creatine kinase enhancer; this is dramatically reflected in dissociation-rate measurements. A deletion of the acidic N terminus (residues 3-56) results in a protein that binds normally to single sites but fails to bind cooperatively to two adjacent sites, suggesting a role of the N terminus in cooperative interactions. In transfection assays, a reporter gene flanked by a single MyoD binding site fails to be activated by cotransfected MyoD expression vectors. In contrast, a reporter with two or more MyoD binding sites is activated by wild-type MyoD but not by N-terminally deleted MyoD. A reporter gene with a single binding site, although not activated by MyoD, can nonetheless compete for expression with a reporter gene containing three sites. Thus, in vivo, a single site can bind MyoD, but occupancy of two or more sites is required for subsequent transcriptional activation.

Animals↗
PubMed1990

Isolation of a microsporidian from a human patient.

Several genera of microsporidia have been identified morphologically in human tissue but none has yet been propagated in vitro. These primitive, obligate intracellular parasitic protozoa are poorly understood pathogens of a wide variety of vertebrates and invertebrates. In humans they are especially important as opportunistic pathogens in AIDS patients. A microsporidian was recovered from a human patient and propagated in vitro. The organism has diplokarya, divides by binary fission, and often is found free in the host cell cytoplasm. The name Nosema corneum is suggested.

Animals↗
PubMed1990

Benefits of epidural methylprednisolone in a unilateral lumbar discectomy: a matched controlled study.

The effects of instilling methylprednisolone acetate (MP) (Depo-Medrol) onto the exposed nerve root during a unilateral lumbar laminotomy (either L4 or L5) for disc excision was studied in 43 patients (primary: 35; repeated procedure: 8). The results were compared with two similarly matched control groups without the steroid drug. All 86 patients preoperatively experienced radicular pain to the calf, and were operated on by one surgeon. Four parameters, studied during the postoperative hospital stay, were compared between the control and MP series. The MP (primary/repeat) groups' (a) stay was reduced by 37/40%, respectively; (b) need for strong narcotic drugs was decreased by 64/70%; (c) need for milder pain medication was decreased by 49/72%; and (d) need for spasm medication was reduced by 77/59%. The paired t test indicated that there is a statistical difference between the MP and control groups' results because of the use of MP, with confidence levels of 0.9927-0.9999 in the primary group, and 0.9806-0.9913 for three of the four parameters in the repeat group. Intraoperative application of epidural steroid drugs such as MP, in a unilateral low-lumbar discectomy, leads to a shorter hospital stay because of less pain and spasm.

Adult↗
PubMed1990

Effect of a ZOE temporary cement on the bond strength of a resin luting cement.

This study was conducted to determine if a eugenol-based temporary cement affected the bond strength of a dual-cure cement to etched enamel. Dicor buttons were cemented to etched enamel surfaces after pretreatment with a non-eugenol containing cement, a eugenol containing cement and a control. This study concluded that shear bond strengths were unaffected by the temporary cement, provided the enamel surface was cleaned with pumice and etched with 37% phosphoric acid.

Acid Etching, Dental↗
PubMed1989

Experience with pneumocystis carinii pneumonia in patients with AIDS.

We have reviewed admission data, some diagnostic tests, treatment and outcome of 31 male homosexual patients infected with the human immunodeficiency virus with 37 consecutive episodes of presumptive Pneumocystis carinii pneumonia treated at the infectious disease unit, Auckland Hospital, between 1985 and 30 June 1988. The median age was 39 years. Eight episodes were proven Pneumocystis carinii pneumonia, 18 satisfied Centres for Disease Control criteria for presumptive Pneumocystis carinii pneumonia and 11 lacked one Centres for Disease Control criterion. Patients began intravenous or oral cotrimoxazole in 32 episodes, initially 20 mg/k/d of trimethoprim component, but since early 1988 10 mg/k/d. In nine episodes treatment was changed to intravenous pentamidine because of side effects or failure to respond while five received pentamidine as their only drug. Cotrimoxazole caused side effects in 20 of 32 episodes (rash in 11) and pentamidine in 10 of 14 (renal impairment in nine). Two patients died (ie, a 5% mortality for all 37 episodes or 8% for 26 proven and Centres for Disease Control presumptive episodes). Median hospital stay for survivors was 11 days. Fourteen other patients have subsequently died a median eight months after the initial episode. Pneumocystis carinii pneumonia is an important infection in patients infected with the human immunodeficiency virus.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Fe:S cluster ligands are the only cysteines required for nitrogenase Fe-protein activities.

Serine substitutions for the five conserved cysteins (residues 38, 85, 97, 132, and 184) have been made in the Azotobacter vinelandii nitrogenase Fe-protein by site-specific mutagenesis. At least moderate levels of enzyme activity (greater than 10% of wild type enzyme) were found for enzymes with serine substitutions at residues 38, 85, and 184; whereas, no activity was detected for enzymes with serines at residues 97 and 132. This is consistent with cysteines 97 and 132 being the four ligands to the Fe:S cluster (two ligands from each of the two identical subunits). Although previous chemical modification studies had implicated these residues as ligands, the earlier results did not portend the new finding that of all the conserved cysteines only these 2 residues are required for a second function of the Fe-protein. Namely, if either cysteine 97 or 132 is replaced, it appears that a functional Fe:S cluster cannot be incorporated into the apo-Fe-protein. The consequence is that these altered Fe-proteins cannot participate either in substrate reduction or in the biosynthesis of FeMo-cofactor, a metallocofactor of the MoFe-protein. These results implicate the Fe:S center of Fe-protein in the biosynthesis mechanism as either a redox partner or Fe:S donor. Additional results suggest that the posttranslational modification of Fe-protein by nifM product is not the insertion of the Fe:S center.

Adenosine Triphosphate↗
PubMed1989

Expression of the three myeloid cell-associated immunoglobulin G Fc receptors defined by murine monoclonal antibodies on normal bone marrow and acute leukemia cells.

Monoclonal antibodies (MoAbs) have been prepared recently that recognize the three cell-surface receptors for the Fc portion of immunoglobulin (Ig), termed Fc gamma RI (MoAb 32.2), Fc gamma R II (MoAb IV-3), and Fc gamma R III (MoAb 3G8) that are expressed on selected subsets of non-T lymphocyte peripheral blood leukocytes. In the blood, Fc gamma R I is expressed exclusively on monocytes and macrophages, Fc gamma R II on granulocytes, mononuclear phagocytes, platelets, and B cells, and Fc gamma R III on granulocytes and natural killer (NK) cells. We have examined the expression of these molecules on normal bone marrow (BM) cells and on leukemia cells from the blood and/or BM in order to determine their normal ontogeny as well as their distribution on leukemic cells. BM was obtained from six normal volunteers and from 170 patients with newly diagnosed acute leukemia. Normal BM cells were found to express Fc gamma R I, II, and III with the following percentages: 40%, 58%, and 56%, respectively. Cell sorting revealed that both Fc gamma R I and Fc gamma R II were detectable on all subclasses of myeloid precursors as early as myeloblasts. Cell sorting experiments revealed that 66% of the granulocyte-monocyte colony-forming cells (CFU-GM) and 50% of erythroid burst-forming units (BFU-E) were Fc gamma R II positive with only 20% and 28%, respectively, of CFU-GM and BFU-E were Fc gamma R I positive. Acute myeloid leukemia (AML) cells expressed the three receptors with the following frequency (n = 146): Fc gamma R I, 58%; Fc gamma R II, 67%; and Fc gamma R III, 26% of patients. Despite the fact that Fc gamma R I is only expressed on monocytes among blood cells, AML cells without monocytoid differentiation (French-American-British [FAB]M1, M2, M3, M6) were sometimes positive for this receptor. However, Fc gamma R I was highly correlated with FAB M4 and M5 morphology (P less than .001). Fc gamma R II was also correlated with FAB M4 and M5 morphology (P = .003). Cells from 11 patients with acute lymphoblastic leukemia were negative for Fc gamma R I, but six cases were positive for Fc gamma R II and III (not the same patients). These studies demonstrate that Ig Fc gamma R are acquired during normal differentiation in the BM at or before the level of colony-forming units. In addition, we show that acute leukemia cells commonly express Fc gamma R.

Acute Disease↗
PubMed1989

Human urine mutagenicity study comparing cigarettes which burn or only heat tobacco.

Cigarette smokers have been reported to void urine which is more mutagenic, as measured in the Ames bacterial mutation assay, than urine voided by non-smokers. Condensate from the mainstream smoke of a cigarette which heats, but does not burn tobacco (test cigarette) showed no evidence of mutagenicity in a battery of in vitro genotoxicity assays under conditions in which condensate from the mainstream smoke of cigarettes that burn tobacco was mutagenic. The objective of this study was to determine whether the absence of mutagenic activity observed in the in vitro assays would be reflected in the urine of smokers of the test cigarette. 72 subjects (31 smokers and 41 non-smokers) were enrolled in a 6-week study, with the smokers randomly divided into 2 groups. The study was designed as a double crossover, with each smoker smoking both test (tobacco-heating) and reference (tobacco-burning) cigarettes. This design allowed each smoker to serve as his or her own control while at the same time allowing comparisons between groups of non-smokers and smokers of both test and reference cigarettes. 24-h urine samples were collected twice a week and concentrated using XAD-2 resin. Urine concentrates were tested in Ames bacterial strains TA98 and TA100, with and without metabolic activation and with and without beta-glucuronidase/aryl sulfatase. Individuals who smoked the test cigarette voided urine which was significantly less mutagenic than that voided when they smoked reference cigarettes. The mutagenicity of urine from smokers who smoked the test cigarette and non-smokers did not differ under any of the assay conditions used in this study.

Animals↗
PubMed1989

Small round cell neoplasm of jaw in a patient with medulloblastoma.

A 24-year-old woman presented with a painful mandibular swelling 6 months after multimodality treatment for a cerebellar medulloblastoma. The tumor was microscopically identical to the cranial neoplasm and a part of widespread dissemination as determined by ancillary studies. Previous concepts of the nonmetastasizing nature of intracranial neuroectodermal neoplasms have been modified by studies on treated cases, surgery being considered a virtual prerequisite for this occurrence. Extracranial neoplastic development of a PNET of CNS origin must be considered in disease-free treated patients up to several years after initial therapy.

Adult↗
PubMed1989

A comparison of radiation doses to the breast in computed tomographic chest examinations for two scanning protocols.

Compared with other radiological examinations in which the breasts are directly exposed, the breast doses involved in computed tomographic (CT) chest examinations are high. A CT protocol which reduces such breast dose has been investigated. Breast doses have been measured for contiguous 10 mm scans and interspaced 3 mm scans. Differences in the breast doses were found between the left and right breasts for both scanning protocols. The dose associated with the interspaced scans was lower by a factor of about two compared with that for the contiguous scans.

Breast↗
PubMed1989

Acute urinary retention associated with prostatic carcinoma.

We describe the prospective evaluation of 90 patients seen at 2 medical centers who presented with acute urinary retention. All patients had a pre-retention history obtained, as well as careful prostate examination, perineal prostate biopsy and followup treatment or monitoring. Prostate cancer was found in 12 of the 90 patients (13.3 per cent), while 1 had metastatic leukemia to the prostate. Of the 90 patients 69 (76.7 per cent) had a palpably benign prostate and 2 malignancies (2.9 per cent) were diagnosed, while 11 malignancies occurred in 21 patients (52.4 per cent) with a suspicious examination. A total of 46 patients (51.1 per cent) underwent further prostate resection and no malignancy was found in any of these specimens: 43 underwent transurethral resection (24.9 gm. average), while 3 underwent open prostatectomy (97 gm. average). Other etiologies of acute retention included benign hyperplasia, other underlying illness, medical procedures, medications, prostatitis and prostatic infarction. Among the 44 patients who did not undergo prostatectomy 13 had treatment of the diagnosed cancer, 9 had resolution of retention and symptoms without intervention, 9 remained catheterized due to severe medical problems, 8 were treated for prostatitis, 2 had discontinuation of sympathomimetic drugs and 1 each underwent urethrotomy, bladder neck incision and resolution of prostatic infarction. In contrast to the older literature in which approximately 25 per cent of the patients presenting with acute urinary retention had prostate cancer, our data suggest a lower incidence. Prostatic biopsy for patients who present with acute urinary retention and a benign examination does not appear to be justified.

Acute Disease↗
PubMed1989

Lipomeningioma.

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Humans↗
PubMed1989

Comparison of hyperbaric and plain bupivacaine with hyperbaric cinchocaine as spinal anaesthetic agents.

In a double-blind study, 90 patients (ASA 1 or 2) received spinal anaesthesia with 2 ml hyperbaric cinchocaine 0.5%, 4 ml hyperbaric bupivacaine 0.5% or 4 ml plain bupivacaine 0.5%. All injections were made in the left lateral position, and the patients turned supine immediately. Hyperbaric bupivacaine produced a significantly faster and a higher dermatomal level of bilateral complete sensory blockade than the other solutions (p less than 0.005 for each). The duration of sensory blockade was significantly longer with plain bupivacaine than with either hyperbaric solution (p less than 0.0005). The intensity of sensory blockade was significantly greater with both bupivacaine solutions than with hyperbaric cinchocaine (p less than 0.05). Onset and intensity of motor blockade were similar with all agents, but motor blockade was of significantly shorter duration with hyperbaric bupivacaine than the other agents (p less than 0.0005). Hyperbaric bupivacaine appears to be the best agent for rapid and intense sensory blockade of intermediate duration. Plain bupivacaine is more appropriate if a longer duration of action but a lower height of blockade are required, and has the advantage of less cardiovascular disturbance.

Aged↗
PubMed1989

Transcatheter closure of atrial septal defects. Experimental studies.

Recent experience with the spring-loaded patent ductus arteriosus (PDA) occluder has demonstrated several advantages of this device in the closure of intracardiac defects compared with previously described techniques. Pathologic and animal model studies were performed to identify which atrial septal defects (ASDs) might be suitable for device closure and to test a new septal closure double umbrella. Fifty specimens from the Cardiac Registry with unrepaired ASD secunda (2 degrees) were analyzed. Mean ASD size was 8 x 10 mm (range, 3 x 4 to 30 x 30 mm); 80% (n = 40) of ASDs were judged closable with the new device. ASD closure was attempted in four lambs with the Rashkind (hooked single umbrella) ASD occluder. One of four umbrellas was correctly positioned; no ASDs were closed. A new double-hinged ("clamshell") umbrella device was designed: eight ASD closures were attempted with this device (defects ranged from 8 to 20 mm in diameter). Six of eight umbrellas were correctly positioned; four of four animals observed more than 1 day appeared to have complete closure on postmortem examination with endothelialization of the device. We conclude that 1) most ASD 2 degrees are far enough from vital structures to permit closure, 2) initial placement of hooked umbrellas is often incorrect and cannot be altered, 3) clamshell double umbrellas were successfully placed in six of eight attempts, and 4) endothelialization of closed ASDs appears complete within weeks of implantation. These preliminary studies appear promising and support testing the clamshell ASD device in clinical trials.

Animals↗