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Biomedical subjects

M Allen

Publications and source records attributed to M Allen.

At least 19 recordsLinked to original sources
PubMed1995

Evolutionary importance for the membrane enhancement of the production of vitamin D3 in the skin of poikilothermic animals.

The photoproduction of vitamin D in the skin was essential for the evolutionary development of terrestrial vertebrates. During exposure to sunlight, previtamin D3 formed in the skin is isomerized to vitamin D3 (calciol) by a temperature-dependent process. Since early land vertebrates were poikilothermic, the relatively slow conversion of previtamin D3 to vitamin D3 at ambient temperature put them at serious risk for developing vitamin D deficiency, thus leading to a poorly mineralized skeleton that could have ultimately halted further evolutionary development of vertebrates on land. We evaluated the rate of isomerization of previtamin D3 to vitamin D3 in the skin of iguanas and found the isomerization rate was enhanced by 1100% and 1700% at 25 degrees C and 5 degrees C, respectively. It is likely that the membrane entrapment of previtamin D3 in its s-cis,s-cis conformation is responsible for the markedly enhanced conversion of previtamin D3 to vitamin D3. The membrane-enhanced production of vitamin D3 ensures the critical supply of vitamin D3 to poikilothermic animals such as iguanas.

Animals↗
PubMed1995

Formoguanamine-induced inhibition of deprivation myopia in chick is accompanied by choroidal thinning while retinal function is retained.

Twenty hatchling chickens were injected intravitreally every 4 days from day 2 to day 16 with dimethyl sulphoxide (DS) in one eye and DS or formoguanamine dissolved in DS (FG.DS) with or without occlusion in the other (FG.DS.MD, DS.MD, FG.DS). At day 16, the FG.DS.MD eyes failed to show the high refractive myopia and showed less axial elongation than that developed by the DS.MD eyes. Electroretinograms indicated that at the dosage used, FG.DS does not eliminate phototransduction. Light microscopy showed choroidal and retinal thinning in DS.MD and FG.DS.MD eyes but less than in FG.DS eyes, suggesting that change in choroidal thickness is unlikely to be the primary cause of form deprivation myopia.

Animals↗
PubMed1995

The fate of the osteotomized free radial forearm osteocutaneous flap in mandible reconstruction.

The radial forearm osteocutaneous free flap has become a standard method of mandible reconstruction. In order to improve the contour of the reconstructed jaw in large resections, especially the anterior defect, the radial forearm bone graft needs to be osteotomized. The bone graft is nourished by small branches of the radial artery via the fascial connections between the skin flap and bone. The effect of the osteotomy, fixation devices, and the angulation of the bone segment on bone viability and eventual bone healing is not known. Forty-two radial forearm osteocutaneous flaps were used for composite mandible reconstruction. In 25 patients, the bone graft required osteotomy to achieve contour, of which 16 required single osteotomy and nine required double osteotomy. In a remaining 17 cases, no osteotomy was performed. Only those patients who had at least a 1-year follow-up were included in this study. The proportion of patients who achieved bone union was similar for both groups (i.e. osteotomy vs. nonosteotomy). Performing osteotomies on the segment of the radius in free osteocutaneous transfers is safe, and it allows for more flexibility in reconstruction, to achieve a natural-appearing jaw.

Adult↗
PubMed1995

Pediatrician's communication style: relationship to parent's perceptions and behaviors.

Investigated physician-parent communication styles and the effects of concordance between parent's desired communication styles and the communication style exhibited by physicians. Subjects were 107 parents of children scheduled for an appointment with a pediatrician at a general medical clinic. Parents and physicians completed rating forms indicating the degree to which parents desired each of four communication styles (information giving, interpersonal sensitivity, partnership, and directing one's own treatment). Parents and physicians also rated the degree to which they believed the physician exhibited each of these four styles. Follow-up interviews with parents assessed the level of satisfaction with the visit, perception that parent's concerns had been addressed, and subsequent telephone calls to the physician. Results indicated that physicians underestimated the degree of interaction desired by the parents. Parent desires for particular communication styles were not predicted by characteristics of the parents. Interaction variables predicted parent perceptions and subsequent need for contact with the physician.

Adolescent↗
PubMed1995

Analysis of HLA-class II DQA1, DQB1, DRB1 and DPB1 in Italian multiple sclerosis patients.

We studied the allelic constitution at the HLA class II DQA1, DQB1, DRB1 and DPB1 in 94 Italian multiple sclerosis (MS) patients and 98 controls. No significant increase in the frequency of DR2 alleles was detected among MS patients, as previously observed both in European and some Italian studies. A slight increase was found for the DQA1*0301 and DQB1*0602 alleles in the MS patients. No significant association was found with the glutamine residue at position 34 of the DQ alpha chain, which was noted previously in MS patients from northern Europe.

Alleles↗
PubMed1995

Altered vascular endothelium integrin expression in psoriasis.

Considerable evidence indicates that microvascular changes observed in psoriasis are a result of vascular proliferation. A critical step in the sequence of events leading to neovascularization involves interactions between endothelial cells and extracellular matrix proteins mediated in part by the integrin family of adhesion molecules. A number of endothelial integrins have been shown to participate in neovascularization, including members of the beta 1, beta 3, and beta 4 subfamilies. To investigate the role of these integrins in psoriasis, specimens of lesional and nonlesional skin were taken from 10 patients with active, untreated plaque disease. Vascular endothelium was labeled with monoclonal antibodies specific for alpha 2, alpha 5, alpha 6, beta 1, av beta 3, and beta 4 integrins. The use of image analysis permitted quantification of immunoperoxidase staining and comparison of endothelial labeling in lesional and nonlesional skin. There was a significant increase in endothelial staining of av beta 3 integrin in lesional compared with nonlesional skin, both in superficial and deep vasculature. In contrast, there was a significant decrease in endothelial beta 4 staining in lesional compared with nonlesional superficial dermal vessels, alpha 2, alpha 5, alpha 6, and beta 1 staining showed no significant difference between the two groups. These results demonstrate an important role of av beta 3 and beta 4 integrins in the microvascular changes of psoriatic lesions.

Adult↗
PubMed1995

Allele-specific HLA-DRB1 amplification of forensic evidence samples with mixed genotypes.

A major problem in analyzing forensic casework samples is the presence of genetic material from more than one individual in the material evidence. For instance, in sexual assault cases the evidence (vaginal swabs) usually contains a majority of vaginal epithelial cells and varying amounts of sperm cells from the perpetrator. Samples with mixed genotypes are also common among other biological evidence materials such as nail scrapes and mixed bloodstains. We have developed an allele-specific amplification system for the highly polymorphic HLA class II DRB1 locus that permits the detection of individual alleles in a sample with mixed genotypes, independent of the initial frequency of the alleles. Using a set of eight allele-specific amplification primers and typing the amplified fragments with sequence-specific probes, most of the 60 DRB1 alleles can be resolved. The method is highly specific and sensitive, with the potential for amplifying 15 copies of a particular allele in a background of 3 x 10(5) copies of other alleles. The method was successfully applied to three forensic cases, where the material evidence consisted of sperm stains on panties, nail scrapes and bloodstains on skin. Thus the DRB1 allele-specific amplification system can be employed for the unambiguous determination of the presence of individual alleles in materials suspected to contain mixed genotypes, even when the alleles of interest constitute only a small fraction of the total DNA.

Alleles↗
PubMed1994

Breast augmentation surgery: a women's health issue.

Surgery to increase breast size is a common procedure. In this paper we examine the reasons why women choose to undergo the procedure, the history of breast enhancement, current surgical approaches, possible complications and their treatment. Driving forces behind the choice to have augmentation surgery appear to be related to feelings of low self-esteem and self-confidence. Although there is a large literature related to breast augmentation, little of it is research-based. The research that there is focuses on complications and their treatment, with an emphasis on capsular contracture. Few of the studies are long-term, although complications have been noted as long as 25 years after initial implantation. There is a need for research into the experience of women undergoing augmentation mammaplasty but, perhaps more importantly, there is also a need to examine ways in which women can be helped to accept themselves as they are.

Breast Implants↗
PubMed1994

PCR-based DNA typing of saliva on stamps and envelopes.

In forensic cases involving mail bombs, extortion, kidnapping or threatening letters, biological evidence such as the saliva used to attach the stamp and seal the envelope could be used for genetic analysis. We have developed a highly sensitive semi-nested PCR method for the HLA-DRB1 locus; suitable for the analyses of very limited amounts of DNA. When applied to a set of stamps and envelopes with saliva from control individuals, typing results were consistent with those obtained using hairs drawn from the same individuals. No interference was found due to DNA from the fingerprints of people handling the letters. The system was applied to three forensic cases with threatening letters. The first case resulted in an exclusion of the suspect. In the second case, the suspect could not be excluded (probability of identical genotype by chance > 0.01). These results demonstrate that biological evidence in cases with threatening letters is amenable to genetic typing.

Base Sequence↗
PubMed1992

Validity of postnatal assessments of gestational age: a comparison of the method of Ballard et al. and early ultrasonography.

This study investigates the accuracy of the postnatal gestational age assessment method of Ballard et al. to predict very preterm, preterm, term, postterm, and small-for-gestational-age infants, with gestational age by early ultrasonography used as the gold standard. Sensitivity, specificity, and predictive value were examined for each gestational age category, with 4193 single live births occurring during the period from 1982 through 1989 with an ultrasonographic examination done by 20 weeks' gestation and a postnatal assessment at 28 to 44 weeks. These data indicate that the postnatal assessment overestimated the gestational age of preterm births, resulting in an underestimation of very preterm and preterm percentages. Nearly three fourths of the postterm births by ultrasonography were misclassified by the method of Ballard et al. because of underestimation of postterm gestational ages. These data indicate that, for research purposes, appreciable misclassification of preterm, postterm, and small-for-gestational-age infants will occur if gestational age is determined by the technique of Ballard et al.

Evaluation Studies as Topic↗
PubMed1992

Hemodynamic effects of oral amiodarone on left ventricular function before and after global ischemia.

We evaluated the hemodynamic effects of amiodarone on left ventricular (LV) function after global ischemia. Amiodarone was administered orally at 15 mg/kg/day for an average of 28 days to a group of 10 dogs. The concentration of amiodarone in serum and LV myocardium was 0.40 +/- 0.24 micrograms/ml and 44 +/- 27.0 micrograms/g, respectively. This experimental group and a control group of 10 dogs each underwent 120 min of aortic cross-clamping with cold crystalloid cardioplegia resulting in an average myocardial temperature of 15 degrees C. LV function measurements by pulse-transit sonomicrometry and Millar solid-state micromanometers were processed by a minicomputer. Compared to the nontreated control group, oral amiodarone for 28 days produced depression of LV contractility which was reflected by lower slope of the end-systolic pressure-volume relation (Evmax), percentage shortening of segment length, left ventricular pressure-segment length loop area, and slope of the end-systolic pressure-segment length relation (Esmax). After ischemia, percentage recovery of LV global function (Evmax and mean velocity of circumferential fiber shortening) and regional function (Esmax) was significantly better in the amiodarone group than in the control group. We conclude that oral amiodarone for 28 days results in a depression of LV contractility but the combination of amiodarone and ischemia does not act synergistically to further depress postischemic LV function.

Administration, Oral↗
PubMed1992

Local tumor recurrence following "radical prostatectomy".

The resurgence of radical retropubic prostatectomy as a commonly employed treatment for organ-confined prostate cancer is largely a result of the reduction in morbidity related to the procedure. One aspect of this reduced morbidity is the potential to preserve potency. The technical points required to perform this procedure must be followed precisely or there is the potential for performing an inadequate cancer operation if these steps are not faithfully followed. We recently encountered a patient with local tumor recurrence because the initial urologist failed to adhere to these principles. A "salvage" procedure was performed.

Adenocarcinoma↗
PubMed1992

Serum magnesium levels in asthmatic patients during acute exacerbations of asthma.

The purpose of this study was to determine whether serum magnesium levels in asthmatic patients during acute exacerbations differ from those of a control population. Twenty-three known asthmatics presenting to the emergency department in acute exacerbation (cases) and 15 nonasthmatic patients (controls) matched for age, sex, race, and socioeconomic status had serum magnesium assays drawn. Admission criteria were: age 18 to 50 years with no history of alcoholism, heart disease, renal disease, or diuretic use. Patients giving a history of pregnancy were excluded. Serum magnesium levels were not significantly different in the two study populations, nor did they correlate with the severity of asthma (mean values: cases, 2.04 +/- 0.159 versus controls, 2.03 +/- 0.134 mg/dL; SD of the difference of the means = .048). An analysis for beta-error demonstrated the true difference of the means to be less than .1 (95% confidence) or less than .13 (99% confidence). In conclusion, serum magnesium levels in asthmatics are not significantly different from those of a control nonasthmatic population. They are not clinically useful for predicting the severity of disease.

Acute Disease↗
PubMed1992

Sex differences in self-disclosure: a meta-analysis.

A meta-analysis of 205 studies involving 23,702 Ss was conducted to determine whether there are sex differences in self-disclosure. Across these studies, women disclosed slightly more than men (d = .18). This effect size was not homogeneous across studies. Several moderator variables were found. Sex of target and the interaction effect of relationship to target and measure of self-disclosure moderated the effect of sex on self-disclosure. Sex differences in self-disclosure were significantly greater to female and same-sex partners than to opposite-sex or male partners. When the target had a relationship with the discloser (i.e., friend, parent, or spouse), women disclosed more than men regardless of whether self-disclosure was measured by self-report or observation. When the target was a stranger, men reported that they disclosed similarly to women; however, studies using observational measures of self-disclosure found that women disclosed more than men.

Female↗
PubMed1992

Minisatellite variant repeat (MVR) mapping: analysis of 'null' repeat units at D1S8.

Minisatellite variant repeat mapping by PCR (MVR-PCR) is a new approach to studying variation in human DNA which analyses interspersion patterns of variant repeats within minisatellite arrays. MVR-PCR has been applied to the hypervariable human minisatellite D1S8 which contains two major classes of variant 29bp repeat units designated a-type and t-type. The MVR-PCR assay uses a- or t-type specific primers, together with an amplimer at a fixed site in the DNA flanking the minisatellite, to reveal the interspersion patterns of variant repeats along an allele. Extreme levels of variation are seen both in the internal structures of individual alleles and in the digital code generated from the two superimposed alleles in total genomic DNA. However, occasional repeat units fail to amplify in MVR-PCR, signifying the existence of further repeat sequence variants termed 'null' or O-type repeats. Although not significant in individual identification, correct genotyping of null repeats is important when using MVR digital codes in parentage analysis. We have therefore characterised these null repeats and show that most null repeats share a common variant repeat sequence. We discuss the possible origins of null repeats and their application to paternity testing and the analysis of minisatellite evolution.

Alleles↗