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Biomedical subjects

L J Davis

Publications and source records attributed to L J Davis.

At least 55 records · Page 3Linked to original sources
PubMed1993

Lectins and superantigens: membrane interactions of these compounds with T lymphocytes affect immune responses.

1. Lectins and superantigens belong to two different families of macromolecules which are able to interact with cells of the immune system. 2. The principal mechanisms by which they modulate immune responses are presented in this review. 3. Possible similarities shared by these proteins and their common mechanisms of action upon immunocytes will be presented along with a brief discussion regarding the role of these molecules in physiological immune responses and human diseases.

Antigens, Bacterial↗
PubMed1993

Learning and memory impairment in older, detoxified, benzodiazepine-dependent patients.

The effects of benzodiazepine dependence on the ability to learn and remember new material (determined with the Auditory-Verbal Learning Test) were studied in 20 detoxified, benzodiazepine-dependent patients who were 55 years of age or older and in a drug-dependence rehabilitation program. The patients were matched approximately for age, sex, and IQ with 20 detoxified, alcohol-dependent patients in the same rehabilitation program and 22 control subjects from a community sample. Neuropsychologic testing was performed a mean of 6 to 10 days after the patients had been completely detoxified from the addicting substance. The benzodiazepine-dependent patients had more difficulty with tests of learning and short-term and delayed recall than did the alcohol-dependent or control group. The difference between the benzodiazepine-dependent patients and the control group was statistically significant. The results suggest that benzodiazepine dependence in older people can cause memory impairment that persists into the early drug-free period.

Aged↗
PubMed1993

Transient rigid lens-induced striae in keratoconus.

We have observed spontaneous development of striae and an enhanced visibility of them after placing rigid gas permeable contact lenses on six patients suspected of having early keratoconus. These fine folds subside upon removal of the rigid lens. This observation assists clinicians with the differential diagnosis of irregular astigmatism when the definitive biomicroscopic signs of keratoconus are either not present or are so subtle that their presence is questionable. Although these striae may not occur in all patients suspected of having early keratoconus, we find that observation of the posterior cornea in the presence of a rigid lens will often confirm the diagnosis of keratoconus. We have not seen similar striae in patients whose clinical presentation is not consistent with early keratoconus.

Adolescent↗
PubMed1993

Personality variables in cocaine- and marijuana-dependent patients.

Khantzian (1985) hypothesized that the drug of choice of patients with substance-dependence disorders reflects an attempt at self-medication. Cocaine- and marijuana-dependent inpatients were compared using the MMPI to test this hypothesis. These two groups of patients did not differ on the standard validity and clinical scales of the MMPI, and their scores were basically similar to a group of alcohol-dependent inpatients and a group of psychiatric patients of similar age. There was no single MMPI code type that was characteristic of either group of substance-dependent patients. It appears that drug of choice had little effect on the MMPI scores of these two groups of substance-dependent patients. These results are not consistent with the theory of self-medication.

Adult↗
PubMed1993

Both the helix-loop-helix and the leucine zipper motifs of c-Myc contribute to its dimerization specificity with Max.

The oncoprotein c-Myc contains two dimerization motifs- the helix-loop-helix (HLH) and the leucine zipper (LZ) - through which c-Myc specifically dimerizes with Max. We substituted regions of the c-Myc HLH and LZ motifs with the corresponding regions of structurally related proteins that do not interact with Max. Specific association of c-Myc with Max was dictated by helices 1 and 2 of the HLH motif and by the LZ. Within helix 2, residues 6 and 7 were important determinants of dimerization specificity. c-Myc and Max proteins with three amino acids inserted between their HLH and LZ motifs interacted efficiently, suggesting that the spacing between the motifs can be varied. Furthermore, alignment of the motifs at the primary sequence level was not obligatory, since Max with the three amino acid insertion could interact with wild-type c-Myc. These findings are consistent with our recently proposed model for the architecture of HLH/LZ domains.

Amino Acid Sequence↗
PubMed1992

Mascara pigmentation of the bulbar conjunctiva associated with rigid gas permeable lens wear.

We present three patients who were found to have unusual pigmentation of the bulbar conjunctiva. The areas, 1 to 2 mm in size, were translucent with dark black dust-like particles randomly placed within well defined borders. These specks were usually elevated, had a granular texture, and appeared to be overlying pingueculae. All three patients wore rigid gas permeable contact lenses, were found to have either a short tear break-up time or deficient tear aqueous layer, had associated 3:00 and 9:00 o'clock staining, and routinely used heavy mascara and/or eyeliner. In one patient, the areas resolved on discontinuing contact lens wear. The elevated areas may be associated with minor discomfort. We propose that a deficient tear layer and drying adjacent to the lens edge may compromise the conjunctival epithelium and prevent efficient washing of the pigment particles from the conjunctiva, allowing these granules to become embedded in the epithelium. Additional causes of conjunctival pigmentation are discussed.

Adult↗
PubMed1992

Substance use disorder diagnostic schedule (SUDDS): the equivalence and validity of a computer-administered and an interviewer-administered format.

In order to evaluate the equivalence of interviewer-administered and computer-administered forms of the substance use disorder diagnostic schedule (SUDDS), both forms were presented to 100 substance-dependent inpatients. An additional 101 psychiatric outpatients were administered one form or the other. For patients who received both forms of the SUDDS, the percentage agreement ranged from 96% for the classification of a lifetime diagnosis of alcohol abuse/dependence to 88% for the classification of current diagnosis of alcohol abuse/dependence (kappa coefficients ranged from 0.709 to 0.865). Overall agreement with a clinician diagnosis (validity) and the two forms of administration varied from 100% for computer-generated diagnosis of current alcohol abuse/dependence to 71% for computer-generated lifetime diagnosis of drug abuse/dependence, when stratified by number of symptoms reported. No consistent differences were found in the performances of the two forms of the SUDDS, and we conclude that they may be used interchangeably.

Adult↗
PubMed1992

Measurement of glycated proteins in human plasma or murine hepatic cytosolic fractions by a competitive enzyme linked immune assay (ELISA).

After planned immunization, a rabbit polyclonal antibody has been produced that recognized the Schiff base moiety of glycated proteins. Using an ELISA technique, antiserum specifically recognized reduced and glycated epitopes on a variety of proteins, and did not react with nonreduced and glycated proteins. The antiserum showed very low cross-reactivity with reduced but not glycated proteins. The assay was also used to determine the degree of ex vivo glycation of serum proteins from diabetic patients or hepatic cytosolic proteins from mice. Thus, this assay may be used to determine the amount of in vitro or ex vivo glycation of blood or tissue proteins.

Animals↗
PubMed1991

The CAL: an MMPI alcoholism scale for general medical patients.

We developed a MMPI alcoholism scale based on adult medical patient samples. Our criterion group consisted of 736 inpatients (525 males; 211 females) diagnosed as having alcoholism according to DSM-III criteria. Three contrast samples that totaled 13,120 individuals were used for control purposes. MMPI items were chosen by means of logistic regression. The 33 items yielded by this procedure formed a provisional scale (CAL, for common alcoholism logistic) that worked equally well for males and females. With new cross-validation samples, with sensitivity (proportion of alcoholics correctly identified) set at 90%, the specificity (proportion of nonalcoholics correctly identified) ranged from 90% to 96% for selected contrast samples. We conclude that this scale shows promise as a screening device in similar populations.

Adult↗
PubMed1991

Self-Administered Alcoholism Screening Test: a comparison of conventional versus computer-administered formats.

The equivalence of paper-and-pencil-administered and computer-administered versions of the Self-Administered Alcoholism Screening Test (SAAST) was investigated with alcoholic inpatients and nonalcoholic psychiatric outpatients. When the two formats were administered in counterbalanced order, total score mean differences were nonsignificant. In addition, mean differences on a short-form version were also nonsignificant. Equivalence was also determined by comparing the two formats in terms of classification agreement (i.e., classification of subjects into alcoholic and nonalcoholic categories). Agreement between the two formats was 95% in both the total score and short-form versions. Implications of these results as well as the advantages and disadvantages of using computer-administered alcoholism screening tests are discussed.

Adult↗
PubMed1991

Expression of active human immunodeficiency virus type 1 protease by noninfectious chimeric virus particles.

To generate nonpathogenic viral particles which express active human immunodeficiency virus type 1 (HIV-1) protease (PR), plasmids containing sequences from the genomes of HIV-1 and Moloney murine leukemia virus (M-MuLV) were constructed. Either the PR coding region alone; the gag, PR, and reverse transcriptase protein-coding regions; or the complete gag and pol protein-coding regions from HIV-1 were substituted for the corresponding regions of a full-length M-MuLV clone to yield the chimeric plasmids pMoHIV-I, pMoHIV-III, and pMoHIV-IV, respectively. Cell lines which express the viral gag polyprotein were isolated for hybrids pMoHIV-I and pMoHIV-III. These cells produced viral particles which contained processed core proteins. Cleavage of the gag polyprotein in the viral particles was inhibited by the HIV-1 PR inhibitor L-687908, indicating that the viral PR is responsible for the observed processing. The hybrid virions were not infectious; analyses indicated that the viral particles contained little or no reverse transcriptase activity. In addition, particles produced by pMoHIV-III transfectants failed to package the viral genomic RNA. The cell line which expresses and processes the HIV-1 gag polyprotein is a safe and effective reagent for the in vivo evaluation of potential inhibitors of the HIV-1 PR.

Animals↗
PubMed1991

Identification of amino acid residues required for Ras p21 target activation.

The Krev-1 gene has been shown to suppress ras-mediated transformation in vitro. Both ras and Krev-1 proteins have identical effector domains (ras residues 32 to 40), which are required for biological activity and for the interaction of Ras p21 with Ras GTPase-activating protein (GAP). In this study, five amino acid residues flanking the ras effector domain, which are not conserved with the Krev-1 protein, were shown to be required for normal protein-protein interactions and biological activity. The substitution of Krev-1 p21 residues 26, 27, 30, 31, and 45 with the corresponding amino acid residues from Ras p21 resulted in a Krev-1 protein which had ras function in both mammalian and yeast biological assays. Replacement of these residues in Ras p21 with the corresponding Krev-1 p21 amino acids resulted in ras proteins which were impaired biologically or reduced in their affinity for in vitro GAP binding. Evaluation of these mutant ras proteins have implications for Ras p21-GAP interactions in vivo.

Amino Acid Sequence↗
PubMed1991

A comparison of the EH-270 corneal topographer with conventional keratometry.

The Marco Model-1 keratometer was compared for accuracy and precision with the El Hage Corneal Topography System (EH-270). Five consecutive readings of three steel calibration balls (40.50 D, 42.50 D, 44.75 D), one PMMA hemisphere (48.00 D), and 14 eyes (seven patients) were obtained using each instrument. Keratometry was found to be statistically more accurate and precise for measuring the two steeper steel balls and the hemisphere. Values obtained from patients demonstrated excellent correlation between keratometry and the EH-270. Although more variability was observed in measuring corneas greater than 43.00 D using the EH-270, we found these differences to be clinically acceptable. The EH-270 has a number of clinical advantages.

Calibration↗
PubMed1991

The value of a new family practice center patient to the academic medical center.

BACKGROUND: Family practice centers are important contributors to the financial viability of academic health centers, although they often are not the direct beneficiaries of their own labor. The greater time commitment and lower costs of most primary care creates significant financial hardships for departments of family medicine in university centers. This study describes the use of inpatient and outpatient health care services by new patients at a university family practice center. METHODS: A sample of 215 new adult enrollees at a university family practice center were examined for a 1-year period after their initial visit to the center. Total billings by the university hospital, specialty services, and the family practice center were tabulated by insurance type. RESULTS: Medicare patients generated the highest average charges (+2501 per patient per year); self-indemnity patients generated the lowest average charges (+301 per patient per year). The largest portion of health services charges was generated by the university hospital inpatient service, which was responsible for approximately 60 cents of every dollar billed to patients in this study. Conversely, the Family Medicine Department billings generated only 17% of the total charges. CONCLUSIONS: The findings of this study indicate that university-based family practice centers are significant contributors to the financial and educational base of the academic health center. If family medicine and associated primary care centers are forced to reduce their size or services because of financial difficulties, the impact will be felt by the university hospitals and by other specialty departments.

Academic Medical Centers↗