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Biomedical subjects

B Walker

Publications and source records attributed to B Walker.

At least 199 records · Page 11Linked to original sources
PubMed1991

Synthetic murine epidermal growth factor sequence 20-31 is mitogenic and angiogenic.

Epidermal growth factor (EGF) and its homologue, transforming growth factor alpha (TGF alpha), are mitogenic, angiogenic and tumour-promoting polypeptides. Much effort has therefore been directed towards the development of EGF/TGF alpha antagonists as a potential cancer therapy. Initial reports that some EGF/TGF alpha synthetic fragments possess EGF-receptor binding activity have not been confirmed in subsequent studies. We have found, however, that the murine EGF B-loop sequence: Ac-[(S-acetamidomethyl)-Cys20,31]-EGF-(20-31)-NH2 [(mEGF-(20-31)] produces biological effects consistent with the parent molecule in bovine, murine, chick and human, but not rat, model systems. In parallel experiments, both mEGF and mEGF-(20-31) elicit migratory, cytoprotective, growth-stimulatory, growth-inhibitory and angiogenic responses. The reverse B-loop sequence, mEGF-(31-20), is also mitogenic and angiogenic. The C-loop sequence, mEGF-(33-42), has no mitogenic or angiogenic activity when applied alone, does not block the mitogenic effect of mEGF, but does block the angiogenic effect of mEGF. It has not been established that the EGF receptor is the target for these fragments, but the results suggest that the residual biological activities of EGF fragments merit further investigation.

3T3 Cells↗
PubMed1991

Conductance measurements in solid phase peptide synthesis. I. Monitoring coupling and deprotection in Fmoc chemistry.

Potentiated conductance shows promise for monitoring the progress of both coupling and deprotection reactions in solid phase peptide synthesis using Fmoc chemistry. Sterically hindered base may be added to the aprotic polar solvents used for synthesis, this induces ionisation of acids formed in the coupling and deprotection reactions, thus giving rise to a conductance signal in the solvent. Changes in this signal allow reactions occurring at the resin to be followed with no degradation of coupling efficiency.

Acylation↗
PubMed1991

Environmental health and African Americans.

As environmental health has taken on immensely increased significance in the prevention of disease, dysfunction, and premature death, its boundaries have been anything but stable. This instability, along with a multitude of demographic, social, and economic currents, have brought into stark relief the increasing demand for scientists who have the skills and knowledge to perform environmental risk assessment and implement effective risk management policies and services. Despite this demand far too few African Americans want, or are prepared, to pursue careers in sciences. This paper describes efforts to address this problem and suggests why such initiatives may not yield the desired results.

Black or African American↗
PubMed1991

Reliability of three clinical measures of muscle tone in the shoulders and wrists of poststroke patients.

Muscle tone was tested at the shoulders and wrists of 49 randomly selected poststroke patients with the use of resting joint position (SJP and WJP), resistance to passive movement or stiffness (SRM and WRM), and angle of appearance of resistance (SAR and WAR). Subjects were tested while seated with their arm supported in a suspension sling adapted for free movement. Five of the first and immediately repeated measurement pairs showed strong correlations and interrater reliability (SJP, .839; WJP, .900; SRM, .886; WRM, .904; SAR, .884 [p less than .05]). The sixth (WAR) showed moderate reliability (.618, p less than .05). Resting joint position measurements were most reliable among subjects with higher tone. The joint first measured had a slight order effect on SRM among subjects with higher muscle tone. Its second measurements were slightly increased over the first among those subjects whose shoulders were measured first and slightly reduced when measured immediately after the wrist. Reliable means of clinical evaluation of muscle tone at the shoulder and wrist are available if the influence of level of tone and the mutual influence of muscles tested are prudently considered.

Aged↗
PubMed1991

A rapid method for quantitating the frequency of peripheral blood cells containing HIV-1 DNA.

This article describes a novel approach to quantitative polymerase chain reactions (PCR). The technique is simple to execute, can be performed in a single tube, and is suitable for automation. In addition, the counting and lysis of low numbers of cells (1-100) can be confirmed by phase contrast microscopy. In this study, the technique was used to determine the frequency of occurrence of DNA from the human immunodeficiency virus (type 1) in leukocyte subsets of peripheral blood mononuclear cells (PBMC) from sero-positive individuals. It was confirmed that the frequency of infected CD4+ T cells varied from 0.01 to 0.0001. In addition, HIV-1 DNA was detected in the B cell/dendritic cell-enriched subpopulation in four of nine HIV-1-positive individuals in the study.

AIDS-Related Complex↗
PubMed1991

High-resolution endovaginal ultrasonography of the endometrium: a noninvasive test for endometrial adequacy.

Endovaginal sonography of the endometrium demonstrates characteristic findings throughout the menstrual cycle. To correlate these findings with histologic criteria for normal endometrial development, we compared endometrial biopsies with ultrasonographic findings. Nineteen cycles were monitored in 18 women with ovarian failure whose endometrial cycles were induced exogenously by sequential transdermal 17 beta-estradiol (E2) and intramuscular progesterone. These subjects underwent ultrasonography of the endometrium prior to the day of progesterone initiation (luteal day +1) and continuing throughout the mid-secretory phase. On luteal day +1, ultrasonography characteristically demonstrated a multilayered endometrium consisting of a hyperechoic perimeter (endometrial-myometrial interface), a hypoechoic inner layer, and a hyperechoic midline (luminal interface). By luteal day +7, a gradual increase in echogenicity of the inner layer was detected, while the inner myometrium remained hypoechoic. Eleven of 19 cycles demonstrated a completely hyperechoic endometrium on luteal day +7 and also demonstrated normal stromal development on endometrial biopsies. Three patients who had endometrial biopsies consistent with their chronological development failed to demonstrate a hyperechoic endometrium by luteal day +7. All five biopsies that were histologically out of phase were detected by ultrasonography. Thus, ultrasonography demonstrated a sensitivity of 100% and a specificity of 62% for the detection of histologically normal endometrial development. Endometrial thickness could not be used to discriminate between biopsies that were normal (13 +/- 1.0 mm) and those out of phase (13.8 +/- 1.8 mm). Endometrial histology demonstrated asynchrony of glands and stroma in nine cases in which ultrasonography correlated with stromal, but not with glandular dating, suggesting that the increased echogenicity may reflect stromal edema.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Suicide by jumping from high-rise hotels. Fulton County, Georgia, 1967-1986.

During a 20-year period from 1967 through 1986, 19 suicidal jumps from high-rise hotels (HRHs) accounted for 24% of all fatal jumping episodes and 1% of all suicides in Fulton County, Georgia, U.S.A. The rate of suicidal jumps from HRHs did not increase during the study period. The number of fatal jumps per hotel-year correlated with the height of the interior hotel atrium. The mean age for all victims was 34 years, and 63% of victims were white males. The majority of victims were local residents who were alone when they jumped and were not registered hotel guests. Registered guests tended to jump from the floor on which their room was located whereas nonregistered individuals tended to jump from the upper-most floors in the hotel. Of 19 HRH jumps, 13 occurred from the inside. Suicide notes were found in 37% of cases. HRH jumps were least common between 6 p.m. and midnight, all decedents were dressed in street clothing, only one was heard to have screamed, and all but one were dead on the scene. Alcohol and drug involvement was minimal. We hope that this information will be useful to those who investigate such deaths and to those who study the behavioral manifestations of suicide.

Adolescent↗