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Biomedical subjects

A Matthews

Publications and source records attributed to A Matthews.

At least 37 records · Page 2Linked to original sources
PubMed1996

Validation of probe EFD52 (D17S26) for forensic DNA analysis.

Validation studies that meet TWGDAM (The Working Group on DNA Analysis Methods) and CAC (California Association of Criminalists) guidelines for RFLP (restriction fragment length polymorphism) analysis were performed with the DNA probe EFD52 (D17S26). These studies demonstrate that the probe EFD52 is suitable for forensic casework. No unexpected DNA banding patterns were obtained from controlled studies examining various tissues, sample consistency over many gels, mixtures of body fluids, various substrates, various contaminants and non-human DNA sources. Of all the animal DNAs tested, only one higher primate yielded a single band to EFD52 hybridization. The sensitivity of EFD52 was shown to be comparable to that of other forensic probes. Population frequency distribution tables were prepared from over 4000 alleles and two-locus studies were conducted on nine forensically useful probes. Black, White, Hispanic and Lumbee Indian populations were found to be in Hardy-Weinberg and linkage equilibrium. Comparisons between victim blood standards and epithelial fractions of mixed strains from sexual assault cases were used to demonstrate the robustness of the EFD52 probe in forensic casework.

Asian People↗
PubMed1996

Development of preterm and full-term infant ability on AB, recall memory, transparent barrier detour, and means-end tasks.

10 preterm and 10 full-term infants were tested longitudinally from 28 to 60 weeks of age on a modified version of the AB task, a nonreaching AB task, a Barrier Detour task, a Means-End task, and Perseveration in the Means-End task. Results show that age-corrected (age since conception) premature infants tolerated longer delays than full-term infants on the modified and nonreaching AB tasks. However, when compared by chronological age (age since birth), there were no group differences on either the reaching or nonreaching AB task. No group differences were found on Barrier Detour, Means-End, or Perseveration in either the age-corrected or chronological age comparisons. The results suggest that the function that mediates modified AB performance is one of memory and not of perseveration or means-end ability. Further, these findings suggest that current proposals about brain development based on single samples of infants may be tenuous. Finally, the results of this study suggest that development of the brain structure(s) that mediate modified AB performance is strongly influenced by experience in the postnatal environment.

Age Factors↗
PubMed1994

African-American factor VII-deficient variants in Georgia (FVII variants).

We studied African-American Factor (FVII)-deficient variants and carriers in Georgia by measuring their levels of FVII antigen (FVIIAG) and FVII procoagulant (FVIIC). Factor VIIAG was determined using enzyme-linked immunoassay (ELISA), whereas FVIIC was measured in two ways: 1) by fibrin clotting methods that employed human recombinant (HRFVIIC), human placental (HPFVIIC), rabbit brain (RBFVIIC), and bovine brain (BBFVIIC) thromboplastins; and 2) by an amidolytic method (AMFVIIC). Prothrombin time tests (PT) were also performed by standard methods. These 4 FVII-deficient patients and 3 carriers demonstrated the following results: PT: 18.2 +/- 6.5 sec; FVIIAG: 73.0 +/- 14.9%; HRFVIIC: 30.6 +/- 20.3%; HPFVIIC: 30.5 +/- 21.4%; RBFVIIC: 25.3 +/- 21.4%; BBFVIIC: 30.6 +/- 17.5%; AMFVIIC: 44.1 +/- 18.3%. We conclude that a group of clinically mild African-American FVII-deficient variants exists in Georgia. This group is characterized by the presence of FVIIAG and decreased FVIIC, using a variety of thromboplastins; and excellent correlation was noted for both human thromboplastins.

Antibodies↗
PubMed1994

Stimulation of oxyradical production of hepatic microsomes of flounder (Platichthys flesus) and perch (Perca fluviatilis) by model and pollutant xenobiotics.

Stimulation of hepatic microsomal NAD(P)H-dependent hydroxyl radical (.OH) production by model compounds, viz. menadione (2-methyl-1,4-naphthoquinone) and nitrofurantoin (N-(5-nitro-2-furfurylidene)-1-aminohydantoin), and pollutant xenobiotics, viz. benzo[a]pyrene (BaP) diones (products of microsomal BaP metabolism), duroquinone (tetramethyl-1,4-benzoquinone--present in pulp mill effluent), and the pesticide lindane (gamma-hexachlorocyclohexane), was examined in flounder Platichthys flesus. Duroquinone was also studied in perch Perca fluviatilis, a freshwater species used in studies of pulp mill effluents in the aquatic environment. Microsomal .OH production was detected by the oxidation of the scavenging agent 2-keto-4-methiolbutyric acid (KMBA), using FeCl3/EDTA as a promotor of the Haber-Weiss reaction (O2- + H2O2 = .OH+OH- + O2). All xenobiotics tested, except lindane, showed synergistic interactions with ferric/EDTA indicative of redox cycling of the xenobiotic. Inhibition of menadione- and nitrofurantoin-stimulated .OH production by superoxide dismutase (50% inhibition) and catalase (80%) indicated respectively the involvement of O2- and H2O2 in .OH production. Maximal rates of KMBA oxidation (Vmax in nmol ethylene/min/mg protein) were similar for NADH and NADPH for menadione (4.58-4.61) and duroquinone (0.26-0.3 [flounder] and 0.93-0.99 [perch]), higher for NADPH than NADH for nitrofurantoin (1.21 and 0.77), and higher for NADH than NADPH for BaP diones, decreasing in the order 1,6-dione (1.12 and 0.14), 3,6-dione (0.75 and 0.25), and 6,12-dione (0.31 and 0.09). Rates for lindane, lacking a redox cycling structure, were low (0.01-0.05). Apparent Km (app. Km) values for xenobiotic were 1-2 orders of magnitude lower for BaP diones than the other compounds. App. Km was lower for NADH than NADPH for 3,6-dione (1.23 and 1.66 microM) and 6,12-dione (0.85 and 1.81 microM), but the reverse of this was found for the 1,6-dione (1.41 and 0.78 microM). App. Km values were almost identical for menadione and duroquinone and lower for NADPH (32-44 microM) than NADH (346-382 microM). The reverse was seen for nitrofurantoin, viz., 76 microM (NADH) and 269 microM (NADPH). Hepatic 1000 g supernatants of P. flesus metabolized BaP to oxyradical-generating products, moreso for beta-naphthoflavone-induced than control fish, and production was reduced by UDP-glucuronic acid for the latter but not the former. The studies indicate a widespread potential for contaminant-stimulated oxyradical generation via redox cycling and other free radical interactions of xenobiotics and their metabolites.

Animals↗
PubMed1992

Transpulmonary angiotensin II formation and pulmonary haemodynamics in stable hypoxic lung disease: the effect of captopril.

The effect of chronic hypoxic lung disease on the activity of the renin-angiotensin (RA) system and the role the RA system plays in the pulmonary vascular changes that accompany hypoxia remain controversial. We have measured transpulmonary generation of angiotensin II (A II) and pulmonary haemodynamics in nine patients with airflow obstruction (mean FEV1 = 0.741) and arterial hypoxaemia (mean PaO2 = 8.4 Pa) before and after captopril. In each patient pulmonary artery pressure, cardiac output, systemic arterial pressure, arterial and mixed venous blood gas tensions and arterial and mixed venous A II were measured at rest and at intervals for a total of 3 h after 25 mg captopril orally. The patients had moderate pulmonary hypertension (mean = 29 mmHg) and slightly raised A II levels (mean = 47.2 pg ml-1) but no step-up in A II levels across the lung. After captopril, both arterial and mixed venous A II levels fell by, on average 80% (SEM 2%), but the transpulmonary gradient for A II remained unchanged for each subject. The systemic arterial pressure fell by an average 18% (SEM 5%). In seven patients pulmonary vascular resistance fell (mean = 31%, SEM 6%) and in two patients it rose. There was no significant change in blood gas tensions. These findings suggest that patients with chronic hypoxic lung disease have decreased conversion of A I to A II in the lung but stimulation of the extra-pulmonary renin-angiotensin system. ACE inhibition appears to cause a fall in PVR in most patients with severe chronic airflow obstruction without deterioration in gas exchange.

Aged↗
PubMed1989

Tumors of the pharyngomaxillary space.

A bulging of the soft palate should alert one to the possibility of a mass in the pharyngomaxillary space. Work-up includes CT scan or MRI and possible needle aspiration. Open biopsy should be avoided. Benign, mixed tumors are most commonly encountered. Surgical excision by external approach is generally advocated.

Adenoma↗
PubMed1988

Effects of naloxone on penile erection in cats.

Male cats were anesthetized with pentobarbital. A Foley catheter was placed in the urinary bladder and physiologic saline, under a head of pressure, was allowed to flow at a constant rate through the bladder. Naloxone, 0.2 mg, caused penile erection in 5 of 11 experiments. The onset of action was 0.5 to 4 minutes, and the duration of the erection was 5 to 36 minutes. In two of three experiments a second injection of naloxone caused a second erection. The erection caused by naloxone was not changed by pre- or posttreatment with morphine or by posttreatment with propranolol. It was suggested that the erection could be due either to altered levels of hormones released from the central nervous system or to removal of reflex inhibitory tone in the spinal cord or sacral parasympathetic ganglia.

Animals↗
PubMed1979

Survey of ophthalmic conditions in a Labrador community. I. Refractive errors.

Of the 745 available members of the population of Nain in Labrador 650 (87%) were screened for refractive errors and ocular disease. Refraction by retinoscopy was done in 553 and axial length measured by an optical method in 514. The results showed that the incidence of low degrees of myopia was higher in Inuit (Eskimos) and those of Mixed Inuit-Caucasian blood in the age groups 10 to 40 than in those over 40. 75% of the myopes came from 20 families in which myopia was present in 2 or more generations. Although there was no significant correlation between the refraction of parents and offspring, there were significant correlations between them for axial length. The axial lenths of the myopic eyes of the Inuit and Mixed populations were significantly longer than emmetropic and hypermetropic eyes. The younger memebers of the population were taller than their parents, and except in female Caucasians axial length showed a significant positive correlation with height. More myopes than emmetropes and hypermetropes achieved grade 8 or more in school. It is suggested that the increased incidence of myopia in the younger age groups might be due to environmental factors interfering with the process of emmetropisation in eyes with a genetic predisposition to myopia by virtue of inheriting a slightlt longer eye. Better nutrition resulting in an increase in stature may also have had some influence.

Adolescent↗
PubMed1977

Cerebrospinal fluid pseudocyst after urinary diversion.

The development of an abdominal mass after urinary diversion in a patient with a ventriculoperitoneal shunt should alert the physician to the possibility of a cerebrospinal fluid pseudocyst. Two pediatric cases of cerebrospinal fluid pseudocysts are presented to illustrate this complication. The etiology, diagnosis and management of the pseudocyst are discussed and the literature is reviewed.

Abdomen↗