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Biomedical subjects

R Davis

Publications and source records attributed to R Davis.

At least 253 records · Page 14Linked to original sources
PubMed1993

Replacement of nephrostomy tube using ureteroscopes.

Replacement of a percutaneous nephrostomy tube can be a difficult task. The often time-consuming procedure involves replacement of a guide wire blindly or under fluoroscopic control, or by using ultrasound after decompression of hydronephrosis. A rigid 8.5F ureteroscope was used successfully to replace nephrostomy tubes in 3 patients with obstructive uropathy secondary to prostate carcinoma and in 1 with an ileoureteral anastomotic leak following radical cystectomy.

Aged↗
PubMed1993

High rate of multilocus deletion in a human tumor cell line.

The nature of recessive mutations at the autosomal locus encoding the purine salvage enzyme adenine phosphoribosyl transferase (APRT) was analyzed in a highly malignant human tumor cell line (the colorectal carcinoma line SW620). Mutant strains resistant to the purine analog 8-azaadenine were obtained in two steps. The first step selection for partial drug resistance produced strains hemizygous for APRT as a result of high frequency loss of one allele. In the second step selection, low frequency base substitutions, small deletions, or insertions produced complete azaadenine resistance. Luria-Delbruck fluctuation analysis of each step of this process indicated that the rate of mutation resulting from allele loss was over 100-fold greater than the rate of mutation resulting from base substitution. There was no reproducible difference in the rate of loss of either of the two APRT alleles even though one maps to a rearranged chromosome. Similarly base substitution rates for the two alleles were not significantly different. Polymorphic loci surrounding APRT on chromosome 16 band q24 were lost together with the selected gene in all isolates while polymorphic loci on the short arm of the chromosome were retained. Thus the high frequency loss of APRT in SW620 appears to be the result of multilocus deletions. SW620 derivatives behaving as heterozygotes were also obtained in the first step selections, but these constituted only 5% of isolates.

Adenine↗
PubMed1993

A dose-ranging study of daily maintenance intravenous foscarnet therapy for cytomegalovirus retinitis in AIDS.

Thirty-two patients with AIDS and previously untreated cytomegalovirus retinitis completed an induction course of foscarnet, 60 mg/kg every 8 h for 14 days, had retinitis stabilize, and were then randomly assigned to receive foscarnet maintenance as either a 90- or 120-mg/kg/day infusion administered over 2 h. Median survival was 157 and 336 days for the 90- and 120-mg/kg/day groups, respectively (P < .001). In an independent, masked analysis of retinal photographs, median time to progression of retinitis was 31 versus 95 days (P = .13). Daily intravenous foscarnet at a dose of 120 mg/kg (adjusted for renal function) resulted in significantly longer survival and tended to increase time to retinitis progression compared to the standard 90-mg/kg/day maintenance dose. Although a substantial increase in the risk of serious toxicity at the 120-mg/kg/day dose was not observed, the small sample size in this trial limited the power to detect differences that might be clinically important.

AIDS-Related Opportunistic Infections↗
PubMed1993

Imaging of the ureters on intravenous urography: does a valsalva help?

A prospective trial, comparing filling of the ureters on routine urography with ureteric filling following a valsalva manoeuvre, was performed. A significantly greater length of ureter was filled by the study patients than controls, allowing this frequently poorly imaged structure to be visualized more consistently.

Adolescent↗
PubMed1993

Cholinergic neuron-specific expression of the human choline acetyltransferase gene is controlled by silencer elements.

Choline acetyltransferase (ChAT) is specifically expressed in cholinergic neurons. To identify control mechanisms regulating the cell-specific expression of the gene encoding ChAT, transient expression of the luciferase gene driven by human ChAT gene 5'flanking sequences was compared in cholinergic and noncholinergic cell lines. Analysis of the gene indicated the presence of two regulatory elements with selective silencing activity. These elements, located between nucleotides -2043 to -3347 and nucleotides -3347 to -6550, act cooperatively to repress promoter activity > 10-fold in a human adrenergic neuroblastoma cell line, SHSY5Y, and a human osteosarcoma cell line, 143 TK-, while exhibiting less than a two-fold effect in cholinergic cell lines. Deletion of either nucleotides -2043 to -3347 or nucleotides -3348 to -6550 reduced cell-specific repression by approximately half. Such differential repression appears to be responsible for the selective expression of the ChAT component of the cholinergic phenotype.

Animals↗
PubMed1993

ScrFI restriction-modification system of Lactococcus lactis subsp. cremoris UC503: cloning and characterization of two ScrFI methylase genes.

Two genes from the total genomic DNA of dairy starter culture Lactococcus lactis subsp. cremoris UC503, encoding ScrFI modification enzymes, have been cloned and expressed in Escherichia coli. No homology between the two methylase genes was detected, and inverse polymerase chain reaction of flanking chromosomal DNA indicated that both were linked on the Lactococcus genome. Neither clone encoded the cognate endonuclease. The DNA sequence of one of the methylase genes (encoded by pCI931M) was determined and consisted of an open reading frame 1,170 bp long, which could encode a protein of 389 amino acids (M(r), 44.5). The amino acid sequence contained the highly characteristic motifs of an m5C methylase. Extensive regions of homology were observed with the methylases of NlaX, EcoRII, and Dcm.

Amino Acid Sequence↗
PubMed1993

Comparison of cognitive-behavioral and supportive-expressive therapy for bulimia nervosa.

OBJECTIVE: The authors compared the effectiveness of 4 months (18 sessions) of cognitive-behavioral and supportive-expressive therapy for bulimia. METHOD: Sixty patients obtained from clinical referrals to an eating disorders program who met modified DSM-III-R criteria for bulimia nervosa were randomly assigned to the two conditions. Treatments were delivered in an individual format, on an outpatient basis, by experienced therapists using treatment manuals. The primary outcome measures were self-induced vomiting, binge eating, and attitudes toward body weight and shape, which were assessed by self-report and structured interview. RESULTS: Fifty patients completed treatment, 25 in each condition. Both treatments led to significant improvements in specific eating disorder symptoms and in psychosocial disturbances. Supportive-expressive therapy was just as effective as cognitive-behavioral therapy in reducing binge eating. Where treatment differences were found, they favored cognitive-behavioral therapy. Cognitive-behavioral therapy was marginally superior in reducing the frequency of self-induced vomiting; 36% of the patients who received cognitive-behavioral therapy and 12% of those who received supportive-expressive therapy abstained from vomiting in the last month of treatment. Cognitive-behavioral therapy was significantly more effective in ameloriating disturbed attitudes toward eating and weight, depression, poor self-esteem, general psychological distress, and certain personality traits. CONCLUSIONS: These results moderately favor cognitive-behavioral therapy over supportive-expressive therapy for bulimia nervosa, but follow-up is required to determine the durability of outcome with both modalities. The findings must be interpreted with caution since the selected clinical sample in this study may not represent the bulimia nervosa population.

Adolescent↗
PubMed1993

HIV risk factors among pregnant and non-pregnant high-risk women in New York City.

A comparison of high-risk pregnant (n = 55) and non-pregnant (n = 598) women from Harlem, New York City on HIV-related drug and sexual risk behaviors was undertaken to identify appropriate prevention and intervention policy recommendations. Clients were recruited for an AIDS risk reduction research demonstration project and were either intravenous drug users (IVDUs) or sexual partners of IVDUs. There was a higher percentage of IVDUs among the non-pregnant women, and no significant differences were found between pregnant and non-pregnant IVDUs in terms of needle risk behaviors. The two groups were also similar in non-injected drug use behaviors. Pregnant women were significantly less likely to use condoms. Recommendations focused on the need for increased HIV risk reduction among high-risk women in general, and increased education efforts among pregnant high-risk women regarding condom use as protection from HIV and the potential consequences of maternal substance use for their children.

Female↗
PubMed1993

Behaviour intervention.

The major problem with assessing behaviour problems in people with intellectual disability is the distortion in the presentations by this group. The clinician should consider early assessment of his or her patient by a behaviour intervention team. Psychotropic medication should be limited to situations where there is a clear benefit to the patient. Ongoing review and critical assessment of all treatments usually enables one to arrive at the best option for the individual.

Aggression↗
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.

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Accident Prevention↗