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Biomedical subjects

R Davis

Publications and source records attributed to R Davis.

At least 19 recordsLinked to original sources
PubMed1992

Developmental regulation of annexin II (Lipocortin 2) in human brain and expression in high grade glioma.

In experiments to identify molecules that might be important in the pathogenesis of glioblastoma multiforme, the most common malignant brain tumor, we found that annexin II (Lipocortin 2, p36), a likely second messenger in several different mitogenic pathways, was highly expressed in tumor tissue of glioblastoma multiforme (9 of 9) and highly anaplastic astrocytoma (2 of 6), but not in astrocytomas of lower pathological grade (0 of 6). We also detected high levels of annexin II expression in fetal brain during the period when radial glia proliferate, although annexin II expression was not detected in normal adult brain. These data demonstrate that annexin II expression is developmentally regulated in the human central nervous system and suggest that the early progenitor radial glia share important characteristics with highly malignant glial tumors.

Amino Acid Sequence↗
PubMed1992

Cycle helmets.

Explore the source record for details and available documents.

Accident Prevention↗
PubMed1992

Renal leiomyosarcoma: plea for aggressive therapy.

We report a case of renal leiomyosarcoma arising from the renal pelvis with immunohistochemical confirmation of the diagnosis. Treatment was extirpative surgery for both primary and metastatic lung lesions as well as adjunctive radiation and chemotherapy. This patient remains disease-free twelve months following treatment.

Adult↗
PubMed1992

Relationship between angiographic infarct size and left ventricular filling.

Infarct size may influence left ventricular filling after acute myocardial infarction. Pulsed Doppler transmitral flow velocities were compared in 47 patients at 7 +/- 6 days following acute myocardial infarction and 47 age-matched controls. Patients were stratified by angiographic infarct size into Groups I, II, III (corresponding angiographic hypokinetic scores less than 2; 2-2.99; greater than or equal to 3 SD/cord). Early diastolic transmitral Doppler flow velocities did not differ between infarct groups but atrial transmitral Doppler flow measurements did: peak A velocity (p = 0.001), A velocity time integral (p less than 0.001), and total velocity time integral (p = 0.001). Compared to controls atrial transmitral Doppler flow was augmented in Group I, whilst atrial and total transmitral Doppler flow were depressed in Group III. Peak A velocity and A velocity time integral were inversely related to infarct size (R = -0.44 to -0.54) and directly to left ventricular ejection fraction (R = 0.59 to 0.65). Large infarct size following myocardial infarction is associated with lower atrial and total transmitral Doppler flow velocities.

Adult↗
PubMed1992

Spinal cord stimulation for multiple sclerosis: quantifiable benefits.

From 1984 to 1991, a quantitative study of 5 multiple sclerosis (MS) patients has been determining benefits from epidural (C7-T1 level) spinal cord stimulation (SCS). The 5 patients (4 male, 1 female; 4 tetraparetics, 1 hemiparetic) were 36-45 years of age having had symptoms for 12-22 years. Five quantitative tests were given prior to and during SCS on 4-8 occasions; 'off' periods were planned and also did occur when the electrode(s) broke (3 patients). With SCS, hand dynamometry showed a 2- to 4-fold increase in the 3 patients with weak hand function. Jebson Hand Time Testing showed a rapidity improvement to 1/2-1/7 of time in the same 3 patients. Minnesota Manipulation Testing with SCS was improved to 1/3-1/2 of time in 2 of these 3 patients tested. Manual muscle strength increased in all patients by 20-50% in 'normal range'. Ambulation in the parallel bars increased with SCS in 2 of the 4 wheelchair patients, while the hemiparetic patient could walk without his cane. All patients showed varying quantifiable improvements with SCS, but over the duration of testing the patients slowly deteriorated. SCS is a rehabilitation option for the weakened MS patient, to be used earlier rather than later in the deterioration of MS patients.

Adult↗
PubMed1992

Cerebellar stimulation for seizure control: 17-year study.

Since 1974, 32 seizure patients have undergone chronic cerebellar stimulation (CCS); 27 have been contacted with 9 (7 spastic, 2 epileptic) continuing to use CCS for an average of 14.3 years (10-17 years). 6 (67%) are seizure-free and 3 (33%) have a reduction of seizure frequency. In the last 2 years, 2 other patients with spastic seizures, who were using CCS for 13 years, died of respiratory illness; 1 had been seizure-free and the other had a reduction. Of the remaining 16 patients (12 spastic, 4 epileptic) who did use CCS for an average of 8.3 years (2-14 years) and now have nonfunctioning stimulators, 5 (31%) continue to be seizure-free, 7 (44%) have a reduction and 4 (25%) have no change or a slight increase. Overall, 23 (85%) patients have benefitted from CCS. Stimulation charge densities were 0.9-2.5 microC/cm2/phase delivered at 10-180 pulses/sec to bilateral electrode pads on the superomedial cerebellar cortex. CCS is relatively safe and nonablative, and could be offered for patients with intractable seizures originating from bilateral or extratemporal foci.

Cerebellar Cortex↗
PubMed1992

Causes of late renal allograft failure in the ciclosporin era.

A single center experience of 514 ciclosporin-treated renal allografts which survived longer than 1 year was reviewed in order to analyze the causes of renal allograft loss beyond the 1st year post-transplantation and the contribution of selected parameters to long-term survival. 83 grafts were lost between 1 and 5 years with the most common causes of graft loss being chronic rejection (54%), death (14%), noncompliance (13%) and sepsis (11%). Actuarial 5-year graft survival rates, decaying from 100% at 1 year, of living related and cadaveric grafts were 88.6 and 79.5%, respectively. Parameters with a substantial influence on long-term survival included the quality of early graft function and incidence of acute rejection in the 1st year post-transplantation. A marker for long-term survival (> 5 years) was a significantly lower serum creatinine (177 mumol/l; < or = 2 mg/dl) at 1 year. We conclude that chronic rejection is responsible for the majority of late graft losses in the ciclosporin era as in the earlier azathioprine period.

Adult↗
PubMed1992

Marginal adaptation of castings made with dual-arch and custom trays.

This study compared the marginal fit of castings made with custom acrylic trays and metal or plastic dualarch impression trays. Standard clinical and laboratory procedures were used to make 36 gold castings for a metal tipodont die. Mean marginal openings were between 25 and 28 microns in all test groups.

Analysis of Variance↗
PubMed1992

Single lung transplantation. Factors in postoperative cytomegalovirus infection.

Thirty-one single lung transplantations were performed between March 17, 1988, and November 1, 1990. Postoperative infection, especially with cytomegalovirus, has been the major cause of morbidity and mortality. Eighteen of the 31 patients were receiving prednisone before transplantation. Every patient was prepared preoperatively with oral cyclosporine 5 mg/kg and azathioprine (Imuran) 2 mg/kg. Every patient received methylprednisolone for 3 days postoperatively, followed by prednisone 1.0 mg/kg/day, oral cyclosporine, and azathioprine. Ten patients additionally had cytolytic therapy with OKT3 and 12 with antilymphocyte globulin. Nine patients had no cytolytic therapy. Cytolytic therapy was chronologic, not randomized. Postoperative infection occurred in 20 patients, 13 of whom had cytomegalovirus infection. Preoperative use of prednisone did not correlate with postoperative infection, cytomegalovirus, or death. Postoperative infection occurred in 17 of 22 patients with cytolytic therapy compared with three of nine without cytolytic therapy (p = 0.035). Cytomegalovirus infection occurred in 13 of 22 with cytolytic therapy and in none of the nine without cytolytic agents (p = 0.003). Therefore preoperative prednisone does not appear to be a contraindication to single lung transplantation. Cytolytic therapy with either OKT3 or antilymphocyte globulin increases the prevalence of postoperative infection with cytomegalovirus and should not be used in patients undergoing lung transplantation.

Contraindications↗
PubMed1992

Effect of temporary cements on the bond strength of a resin cement.

This study evaluated the effect of temporary cements with or without eugenol on the bond strength of a dual-cure resin cement to dentin. Etched, silanated Dicor buttons were bonded to dentin surfaces after pretreatment with the cements. The buttons were sheared in an Instron testing machine. The results showed that shear bond strength is not affected by the temporary cements, if the dentin is cleaned with pumice and treated with Prisma Universal Bond 3 dentin bonding system.

Analysis of Variance↗
PubMed1992

Sealing ability of two intermediate restorative materials in bleached teeth.

This study compared the radicular penetration of bleaching agents in endodontically treated teeth containing an IRM base, a Cavit base, and no base. Forty-five extracted human maxillary central incisors treated with conventional endodontic therapy with laterally condensed gutta percha and sealer were randomly divided into three groups: (1) Cavit base, (2) IRM base and (3) no base. In groups 1 and 2, a 3.5 mm thickness of base material was placed at the time of obturation. After storage in saline for 1 week, the teeth were bleached with a mixture of 35% hydrogen peroxide and sodium perborate, combined with a 10% methylene blue dye solution, using a combination thermocatalytic and non-thermocatalytic bleaching technique. The apical distance of dye penetration was measured. The control group demonstrated dye penetration to the apex, indicating that a base is required to prevent leakage of bleaching agents when this combination of bleaching techniques is used. The mean distance of leakage was 3.43 mm (+/- 1.14) for the Cavit group and 5.94 mm (+/- 1.72) for the IRM group. Analysis with a t-test revealed that Cavit was a more effective barrier to leakage than IRM (T = 4.20, P less than 0.001).

Borates↗
PubMed1992

Root fracture with dentin-retained posts.

The purpose of this in vitro study was to compare the incidence of incomplete root fractures occurring in teeth with and without dentin-retained posts. Eighty extracted human mandibular canines were treated as follows: 20 teeth (controls) received pulpectomies using broaches and sodium hypochlorite; 60 teeth received endodontic therapy with laterally condensed gutta percha. Of those 60 teeth, 20 teeth received Flexi-posts, 20 received Vlock dentin-retained posts, and 20 teeth had no posts placed. All teeth were stained with 5% Oil-Red-O stain for 5 days and sectioned at four levels. The sections were then examined under a stereomicroscope at x20 power. No complete fractures were found. Incomplete fractures were found in two teeth from the endodontic treatment only group, two teeth from the Flexi-post group, and two teeth from the Vlock group. None of the teeth in the control group were fractured. Based upon these results, it was concluded that: 1) Flexi-post and Vlock post placement is no more likely to cause root fracture than is conventional endodontic therapy alone; and 2) incomplete root fractures are more likely to be found in teeth with conventional endodontic therapy than in teeth not treated endodontically.

Cuspid↗
PubMed1992

Motor behavior and motor nervous system function in the nematode Ascaris suum.

Ascaris suum has a nervous system that is very simple both numerically and morphologically. It comprises only 298 neurons almost all of which are extremely simple in shape. Extensive anatomical descriptions of the morphology of neurons and of their synaptic connections, together with the study, by using intracellular recording techniques, of their physiological properties, have led to a prediction of how the motor nervous system controls behavior. Subsequent discovery of endogenous neuropeptides that have potent activity on subsets of the motor neurons suggests that the description of the motor circuitry is more complex than is apparent from its anatomy.

Amino Acid Sequence↗
PubMed1991

PCR-detected genital papillomavirus infection: prevalence and association with risk factors for cervical cancer.

In an investigation conducted in student health clinic patients, the polymerase chain reaction was used to detect human papillomavirus (HPV) DNA, thereby allowing measurement of the prevalence of HPV infection and study of the association between HPV infection and risk factors for cervical cancer. Of 159 women eligible to participate, 105 (66%) provided a specimen of cervical cells for HPV typing, and also answered an interviewer-administered questionnaire which sought information on risk factors for cervical cancer. Nucleic acid extracted from cervical cells was screened with primers for HPV types 6, 11, 16, 18, 33 and with an HPV Consensus primer. Overall, the prevalence of HPV infection was 18.1%, while for HPV-6/11 it was 2.9% and for HPV-16/18 it was 10.5%. There were statistically significant increases in risk of HPV infection with a history of ever having smoked cigarettes (overall, and for HPV-16 alone) and with a history of usually having sexual intercourse during menstrual periods (overall, but not for HPV-16), and these associations were independent of the effects of age at first sexual intercourse and number of sexual partners. The latter 2 variables, as well as the total number of occasions of sexual intercourse, a history of anal intercourse, and a history of ever having used oral contraceptives, were not associated with statistically significant alterations in risk of HPV infection.

Adult↗
PubMed1991

A controlled trial comparing foscarnet with vidarabine for acyclovir-resistant mucocutaneous herpes simplex in the acquired immunodeficiency syndrome. The AIDS Clinical Trials Group.

BACKGROUND AND METHODS: Most strains of herpes simplex virus that are resistant to acyclovir are susceptible in vitro to both foscarnet and vidarabine. We conducted a randomized trial to compare foscarnet with vidarabine in 14 patients with the acquired immunodeficiency syndrome (AIDS) and mucocutaneous herpetic lesions that had been unresponsive to intravenous therapy with acyclovir for a minimum of 10 days. The patients were randomly assigned to receive either foscarnet (40 mg per kilogram of body weight intravenously every 8 hours) or vidarabine (15 mg per kilogram per day intravenously) for 10 to 42 days. In the isolates of herpes simplex virus we documented in vitro resistance to acyclovir and susceptibility to foscarnet and vidarabine. RESULTS: The lesions in all eight patients assigned to foscarnet healed completely after 10 to 24 days of therapy. In contrast, vidarabine was discontinued because of failure in all six patients assigned to receive it. The time to complete healing (P = 0.01), time to 50 percent reductions in the size of the lesions (P = 0.01) and the pain score (P = 0.004), and time to the end of viral shedding (P = 0.006) were all significantly shorter in the patients assigned to foscarnet. Three patients had new neurologic abnormalities while receiving vidarabine. No patient discontinued foscarnet because of toxicity. Although initial recurrences of herpes simplex infection after the index lesion had healed tended to be susceptible to acyclovir, acyclovir-resistant infection eventually recurred in every healed patient, a median of 42.5 days (range, 14 to 191) after foscarnet was discontinued. CONCLUSIONS: For the treatment of acyclovir-resistant herpes simplex infection in patients with AIDS, foscarnet has superior efficacy and less frequent serious toxicity than vidarabine. Once the treatment is stopped, however; there is a high frequency of relapse.

Acquired Immunodeficiency Syndrome↗