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Biomedical subjects

A Young

Publications and source records attributed to A Young.

At least 289 records · Page 16Linked to original sources
PubMed1986

Understanding face recognition.

The aim of this paper is to develop a theoretical model and a set of terms for understanding and discussing how we recognize familiar faces, and the relationship between recognition and other aspects of face processing. It is suggested that there are seven distinct types of information that we derive from seen faces; these are labelled pictorial, structural, visually derived semantic, identity-specific semantic, name, expression and facial speech codes. A functional model is proposed in which structural encoding processes provide descriptions suitable for the analysis of facial speech, for analysis of expression and for face recognition units. Recognition of familiar faces involves a match between the products of structural encoding and previously stored structural codes describing the appearance of familiar faces, held in face recognition units. Identity-specific semantic codes are then accessed from person identity nodes, and subsequently name codes are retrieved. It is also proposed that the cognitive system plays an active role in deciding whether or not the initial match is sufficiently close to indicate true recognition or merely a 'resemblance'; several factors are seen as influencing such decisions. This functional model is used to draw together data from diverse sources including laboratory experiments, studies of everyday errors, and studies of patients with different types of cerebral injury. It is also used to clarify similarities and differences between processes for object, word and face recognition.

Attention↗
PubMed1986

HLA and rheumatoid arthritis: a combined analysis of 440 British patients.

Four hundred and forty unrelated British Caucasoid patients with rheumatoid arthritis (RA) have been HLA typed for class I and class II antigens. Analyses of HLA antigen associations were performed on the overall group and in patient subsets selected according to particular disease parameters or sex, or both. The results confirm previously reported positive associations of HLA-DR4, Dw4, and DRw53 and negative associations of HLA-DR2 and DR7 with RA. Patients subsets with severe erosions, seropositivity, and features of extra-articular disease showed a stronger association, also confirming earlier reports. The link between HLA and disease severity was emphasised by a significant trend of increased Dw4 frequency with increasing severity of radiological erosions. In addition, a positive association of RA with HLA-A2 was observed and a strong negative association with DR3. The frequency of HLA-B27 was significantly increased in patients with subluxation of the spine. Differences were observed between male and female patients in relation to the HLA association. In men an increase in the frequency of the haplotype HLA/Dw4/DR4/Bw62/Cw3/A2 was observed. This showed no relationship with parameters of disease severity other than extra-articular disease. In women only class II antigens (DRw53/Dw4/DR4) showed an increased frequency. This increase was strongly associated with disease severity. A significant decrease of this class II association was observed with increasing age of disease onset; this was not seen in men.

Adolescent↗
PubMed1986

Propranolol does not impair exercise oxygen uptake in normal men at high altitude.

Decreased maximal O2 uptake (VO2max) and stimulation of the sympathetic nervous system have been previously shown to occur at high altitude. We hypothesized that tachycardia mediated by beta-adrenergic stimulation acted to defend VO2max at high altitude. Propranolol treatment beginning before high-altitude (4,300 m) ascent reduced heart rate during maximal and submaximal exercise in six healthy men treated with propranolol (80 mg three times daily) compared with five healthy subjects receiving placebo (lactose). Compared with sea-level values, the VO2max fell on day 2 at high altitude, but the magnitude of fall was similar in the placebo and propranolol treatment groups (26 +/- 6 vs. 32 +/- 5%, P = NS) and VO2max remained similar at high altitude in both groups once treatment was discontinued. During 30 min of submaximal (80% of VO2max) exercise, propranolol-treated subjects maintained O2 uptake levels that were as large as those in placebo subjects. The maintenance of maximal or submaximal levels of O2 uptake in propranolol-treated subjects at 4,300 m could not be attributed to increased minute ventilation, arterial O2 saturation, or hemoglobin concentration. Rather, it appeared that propranolol-treated subjects maintained O2 uptake by transporting a greater proportion of the O2 uptake with each heartbeat. Thus, contrary to our hypothesis, beta-adrenergic blockade did not impair maximal or submaximal O2 uptake at high altitude due perhaps to compensatory mechanisms acting to maintain stroke volume and cardiac output.

Adult↗
PubMed1986

Angiographic and interventional radiologic considerations in liver transplantation.

Of 46 liver transplantations performed, 15 patients are alive at follow-up intervals from 2 to 50 months. The most common indications for liver transplantation were biliary atresia, cirrhosis, and neoplasia. About 50% of the patients had pre- and/or postoperative angiograms. Additional material was available from pretransplant workups in patients subsequently shown to be unsuitable for transplantation. Of 13 preoperative angiographic studies, portal vein patency was confirmed in two, inferior vena caval (IVC) patency was confirmed in two, and diffuse neoplasm was identified in three. These patients subsequently had transplants. Conditions precluding liver transplantation in six patients were inadequate portal vein size (less than 5 mm) in two, occluded IVC or portal vein in one each, nonvisualized portal vein in one, and neoplasm localized to one lobe in one. Postoperatively 18 vascular studies identified hepatic arterial compromise in nine, postbiopsy arteriovenous fistula in two, and bleeding from a right adrenal artery in one. Postoperative venography showed thrombosis or occlusion of the IVC in five, portal vein thrombosis in one, and splenic vein thrombosis in one. Of the 18 postoperative angiograms, 12 demonstrated findings considered threatening to the transplants' survival. Six of 18 studies demonstrated findings considered compromising to the transplant. Of the nine postoperative cholangiographic studies, six diagnoses were considered threatening to transplant survival: obstruction of the biliary-enteric anastomosis in four, leakage from the biliary-enteric anastomosis in one, and an abscess from biliary leakage in one.

Adolescent↗
PubMed1986

HLA and rheumatoid arthritis: susceptibility or severity?

An analysis of data collected on 440 British Caucasoid rheumatoid arthritis patients has confirmed positive association with HLA-DR4, Dw4, DRw53, and A2 and negative associations with HLA-DR2, 3, and 7. HLA-DR4 is more associated with RA 'severity' than with RA 'susceptibility', when measured by the parameters of ARA classification, seropositivity, severity of erosions and extra-articular manifestations. The association between HLA-A2, Cw3, Bw62, DR4, DRw53, and Dw4 and extra-articular disease has been confirmed in this study. The analysis of HLA and RA severity with respect to sex showed high frequencies of DR4, Dw4, and DRw53 in females, which increased in those with severe erosions, seropositivity or extra-articular disease. In males with RA, the disease appears to be associated not only with DR4, Dw4 and DRw53, but also with A2, Cw3 and Bw62. However, no significant differences in these antigen frequencies were found between male patients with severe RA and those without. Despite a significant decrease in the frequencies of DR3, B8 and A1 in most RA patient subsets, RA patients with Sjogren's syndrome showed a marked increase of A1 and B8 and patients with auto-antibodies had a significant increase in HLA-DR3 frequency when compared with patients without these features.

Arthritis, Rheumatoid↗
PubMed1986

HLA antigen associations with radiological changes in the hands, feet, and cervical spines in early rheumatoid arthritis.

Clinical, laboratory, and genetic features measured at the onset of rheumatoid arthritis in 100 patients were compared with the severity of radiological changes in the hands and feet and in the cervical spines at a mean of 7.7 years. HLA-Dw4 was associated with more severe (p = 0.009) and HLA-Dw2 with less severe (p = 0.02)radiological changes in the hands and feet but the single strongest correlation with the severity of peripheral erosions was rheumatoid factor (p = less than 0.0001). Although none of the standard clinical or laboratory parameters correlated with severity of cervical spine changes, the presence of HLA-Dw2 and/or HLA B7 cross-reactive group were associated with more severe radiological changes in the cervical spine (p less than 0.02). Discriminant analysis selected certain standard laboratory parameters which in combination provided the most powerful prognostic index of radiological outcome in the hands and feet which was correct in 82 per cent. The addition of HLA data did not improve this figure. Conversely, the combination of the presence of HLA-Dw2, B27, and older age of onset of disease was found to be the most powerful predictor of the development of cervical spine changes and successfully predicted this complication of RA in 73 per cent.

Adult↗
PubMed1985

Reflex inhibition of the quadriceps after meniscectomy: lack of association with pain.

We have examined the severity and duration of reflex inhibition of quadriceps activation after arthrotomy and meniscectomy, its relationship with pain, and the effect of local anaesthesia on this relationship. Fourteen men, on completion of medial meniscectomy by arthrotomy, received either 10 ml (B10 group) or 15 ml (B15 group) of 0.5% bupivacaine hydrochloride ('Marcaine Plain') into the knee, or no injection (control group). Reflex inhibition of quadriceps was measured as the percentage reduction, from the ipsilateral preoperative value, in the integrated surface electromyogram recorded during maximal voluntary isometric contractions with the knee in extension. Pain during each contraction was recorded on a linear analogue scale. Unoperated limbs showed no evidence of quadriceps inhibition. In the operated limbs, at 1-2 h post-operatively, controls had both severe inhibition (median = 62%) and severe pain on attempting a maximal quadriceps contraction. The B10 group had similar inhibition but less pain (P less than or equal to 0.005, Wilcoxon 2-sample, 1-tailed test). In the B15 group both inhibition (P less than or equal to 0.05) and pain (P less than or equal to 0.01) were less than in the controls. These effects of bupivacaine had been lost by 4-5 h post-operatively. At 3-4 days, inhibition was still severe (median = 75%) in all three groups of patients but pain was only mild or absent. At 10-15 days, median inhibition was still 35%, but there was little or no pain. We conclude that postmeniscectomy inhibition is not simply due to perceived pain but is due, at least in part, to stimuli from the knee.

Adult↗
PubMed1985

The size and strength of the quadriceps muscles of old and young men.

The mean isometric strength of the stronger quadriceps muscles of 12 healthy men in their seventies was 39% less than that of 12 healthy men in their twenties (P less than 0.001). The cross-sectional area of the quadriceps was measured at mid-thigh, by ultrasound scanning; the older men's stronger quadriceps were 25% smaller (P less than 0.001). The ratio of the stronger quadriceps' strength to its cross-sectional area was very similar in the old men to values obtained previously for both old and young women, but averaged 19% less than in the young men (P less than 0.02). Quadriceps size and strength were correlated in the old men (r = 0.77, P = 0.03) but not in the young men (r = 0.15). The principal axis of the relationship between quadriceps size and strength in the old men was very similar to those previously reported for both old and young women. The quadriceps strength of some young men is greater than would be expected from the size of the muscle.

Adult↗
PubMed1985

Molecular cloning and partial sequencing of hepatitis A viral cDNA.

Hepatitis A virus was purified from infected monkey kidney cell cultures, and the viral RNA was used to synthesize double-stranded cDNA. This cDNA was cloned either after insertion into a plasmid-primed synthesis system or after insertion into the PstI site of pBR322. The resulting clones were mapped by restriction endonuclease analysis and by cross hybridization of the viral inserts to generate a composite map which represented at least 97% of the viral genome, lacking ca. 220 bases from the 5' end of the genome. The clones were verified to be hepatitis A virus specific based on their positive hybridization to viral RNA and to total hepatitis A virus-infected cellular RNA from a heterologous marmoset host system. The nucleotide sequence of 3,054 base pairs of cDNA homologous to the 5' half of the viral genome was determined, and an open reading frame of 854 consecutive coding triplets was identified. In addition, sequences which encode the VP-1 and VP-3 viral structural proteins were located in the nucleotide sequence.

Amino Acid Sequence↗
PubMed1985

Evidence for reduced thermic effect of insulin and glucose infusions in Pima Indians.

Several authors have reported a reduced thermic effect of food in obese subjects. The hyperinsulinemic-euglycemic clamp technique has been used to measure one component of the thermic effect of food, insulin and insulin-mediated glucose disposal. We used this technique to measure the thermic responses to insulin and glucose infusions in 120 glucose-tolerant Pima Indians, a population with a high prevalence of obesity. During high-dose insulin infusions (400 mU/m2 per min) the measured increase in energy expenditure (MEE), 150 +/- 6 cal/min, was greater than the predicted increase in energy expenditure (PEE), 72 +/- 2 cal/min, for glucose storage as glycogen. During low-dose insulin infusions (40 mU/m2 per min) the mean MEE, 6 +/- 5 cal/min, was not significantly different from zero and was not greater than the mean PEE, 9 +/- 1 cal/min. These data were in contrast to results obtained from Caucasians by others and suggested a markedly reduced thermic effect of low-dose insulin and glucose infusions in Pima Indians. We also studied 23 glucose-tolerant male Caucasians and compared their results with the results from male Indians matched for glucose storage rates and obesity. The results showed that the thermic response to insulin and glucose infusions was similar in the two racial groups during high-dose insulin infusions but was markedly reduced in the Indians compared with the Caucasians during low-dose insulin infusions.

Adolescent↗
PubMed1984

Preventing fetal alcohol effects: effectiveness of a demonstration project.

The Pregnancy and Health Program (PHP) was established in 1979 to develop effective methods of intervening in maternal alcohol abuse during pregnancy in a metropolitan US community. Services provided over a two-year period included public and professional education, an alcohol and pregnancy information and crisis telephone line, screening for alcohol problems in selected prenatal clinics, treatment and support for women concerned about their drinking during a pregnancy, and help for children possibly affected in utero by alcohol. Evaluation of PHP's educational programmes showed significant increases in awareness and knowledge of the risks associated with drinking during pregnancy, among both the public and health professionals in the community. Information was provided by telephone to over 2400 persons, including one in every 44 pregnant women in the community. A total of 304 pregnant women were personally given information as well as treatment for alcohol problems when necessary. For women seen personally, a significant decrement in drinking was associated with programme entry, which was in turn related to healthier infants at birth. This two-year programme established that intervention in pregnancy drinking is essential and feasible. Screening techniques developed by PHP simplify detection of excessive drinking. Education coupled with effective screening and referral to treatment when needed make reduction of fetal alcohol effects a goal within reach for all communities.

Ethanol↗
PubMed1984

Association of HLA-DR4/Dw4 and DR2/Dw2 with radiologic changes in a prospective study of patients with rheumatoid arthritis. Preferential relationship with HLA-Dw rather than HLA-DR specificities.

Patients admitted to a prospective study within a year of onset of suspected rheumatoid arthritis showed a positive correlation between HLA-Dw4 and the eventual severity of peripheral radiologic changes. Dw4 and DR4 were strongly associated with severity of erosions when analysis was restricted to each of the following: patients with erosions, those under 50 at onset, and all females. Relationships were consistently stronger with Dw4 than with DR4. Another D-related specificity, MT3, was positively correlated and Dw2/DR2 negatively correlated with erosions.

Age Factors↗
PubMed1984

Hypophosphataemic osteomalacia and myopathy: studies with nuclear magnetic resonance spectroscopy.

A patient with familial adult-onset hypophosphataemia, whose myopathy was closely related to the plasma phosphate concentration, was investigated by phosphorus nuclear magnetic resonance spectroscopy (31P n.m.r.) in vivo of the right flexor digitorum superficialis muscle. During hypophosphataemia induced by stopping oral phosphate a significant reduction in measured muscle strength occurred, but the ratios of the intramyocellular levels of phosphocreatine (PCr), adenosine triphosphate (ATP) and inorganic phosphate (Pi) remained unchanged at rest. During exercise these levels changed, as did the intramyocellular pH, but they did not differ from the pattern previously recorded in normal subjects. In four adults with inherited infantile-onset hypophosphataemia (vitamin D-resistant rickets, VDRR) without myopathy, the n.m.r. measurements were normal at rest and during exercise. In one patient with inherited hyperphosphataemia (tumoral calcinosis) the resting PCr: Pi ratio was significantly reduced.

Adenosine Triphosphate↗
PubMed1984

Size and strength of the quadriceps muscles of old and young women.

Muscle weakness and wasting may be evaluated objectively by dynamometry and compound ultrasound imaging. We have measured the voluntary isometric strength of the quadriceps muscles of healthy women in their 70s (n = 25) and in their 20s (n = 25) and have compared it with the mid-thigh cross-sectional area of the same muscles. The two groups of women showed similar variability when strength was measured on consecutive days (coefficients of variation: 8%). The older women were 35% weaker than the young women (P less than 0.001) and their quadriceps cross-sectional area was 33% less (P less than 0.001). Quadriceps strength and cross-sectional area were correlated (r = 0.66, P less than 0.001, elderly; r = 0.53, P less than 0.01, young) and the principal axis of the relationship was closely similar for the two groups of women. There is therefore no difference in the intrinsic strength of the quadriceps muscles of healthy women in their third and eighth decades. This report also provides normative data for the objective evaluation of quadriceps weakness and/or wasting in female patients. The techniques involved are straightforward, the dynamometer is easily made, and compound ultrasound imaging is widely available.

Adult↗