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Biomedical subjects

D A Allen

Publications and source records attributed to D A Allen.

At least 37 records · Page 2Linked to original sources
PubMed1992

Lung innervation and the hemodynamic response to 7% sodium chloride in hypovolemic dogs.

A pulmonary vagal reflex triggered by passage of hypertonic saline through the pulmonary circulation has been proposed as one of the mechanisms by which hypertonic saline resuscitates dogs in hemorrhagic shock. Thirteen anesthetized dogs with denervated left lung lobes were subjected to a standard hemorrhage model to evaluate this purported reflex. We then infused 7% NaCl (4 ml/kg) into either the innervated (six dogs) or the denervated (seven dogs) pulmonary circulation. There were no differences in cardiac output, mean arterial pressure, right atrial pressure, heart rate, or peripheral vascular resistance between groups during a 1 hr period after 7% NaCl infusion. Changes in hematocrit, total plasma protein, and osmolality after 7% NaCl administration suggested that plasma volume expansion had occurred and was similar between groups. We conclude that a pulmonary reflex elicited by hypertonic saline does not contribute to the beneficial hemodynamic effects associated with administration of 7% NaCl during hemorrhagic shock.

Animals↗
PubMed1991

The dark side of Venus: near-infrared images and spectra from the Anglo-Australian observatory.

Near-infrared images and spectra of the night side of Venus taken at the Anglo-Australian Telescope during February 1990 reveal four new thermal emission windows at 1.10, 1.18, 1.27, and 1.31 micrometers, in addition to the previously discovered windows at 1.74 and 2.3 micrometers. Images of the Venus night side show similar bright and dark markings in all windows, but their contrast is much lower at short wavelengths. The 1.27-micrometers window includes a bright, high-altitude O2 airglow feature in addition to a thermal contribution from the deep atmosphere. Simulations of the 1.27- and 2.3 micrometers spectra indicate water vapor mixing ratios near 40 +/- 20 parts per million by volume between the surface and the cloud base. No large horizontal gradients in the water vapor mixing ratios were detected at these altitudes.

Astronomy↗
PubMed1991

Hypertonic saline/dextran resuscitation of dogs with experimentally induced gastric dilatation-volvulus shock.

We investigated small-volume (5 ml/kg) 7% NaCl in 6% dextran 70 (HS/D70) as an alternative to large-volume (60 ml/kg) 0.9% NaCl for treatment of experimentally induced canine gastric dilatation-volvulus (GDV) shock. The stomach was surgically displaced and then distended with an intragastric balloon in 11 dogs anesthetized with pentobarbital. All dogs were subjected to GDV for 180 minutes before partial decompression and resuscitation. Hemodynamic values, blood gas values, and plasma volume were measured during control, shock, and resuscitation periods. Resuscitation started with 1 group (n = 6) receiving 5 ml of HS/D70/kg, iv, over 5 minutes, and the other group (n = 5) receiving 60 ml of 0.9% NaCl/kg, IV, over 60 minutes. Both groups received a surgical maintenance dosage (20 ml/kg/h) of 0.9% NaCl after initial resuscitation. Resuscitative effects of small-volume HS/D70 were similar to large-volume 0.9% NaCl during the first hour of treatment; however, cardiac output was significantly higher in the HS/D70 group for the last 2 hours of resuscitation. Changes in heart rate, left ventricular pressure change, and systemic vascular resistance appeared to be responsible for improved perfusion. Mixed venous oxygen partial pressure data supported improved perfusion in the HS/D70 group. Packed cell volume remained higher in the HS/D70 group, indicating less hemodilution and improved oxygen delivery. Resuscitation of this GDV-induced shock model was better sustained with small-volume HS/D70, compared with conventional large-volume 0.9% NaCl.

Animals↗
PubMed1991

Vagotomy alters the hemodynamic response of dogs in hemorrhagic shock.

We examined the hemodynamic response of severely hemorrhaged dogs to vagotomy to further define the role of vagal innervation in circulatory control during severe hemorrhage. When the cervical vagi were severed in severely hemorrhaged, pentobarbital-anesthetized dogs, MAP decreased immediately after vagotomy and remained lower than in vagal-intact dogs. Cardiac output (CO) and heart rate (HR) also remained lower in the vagotomized dogs. When 45 ml/kg of 0.9% NaCl was administered to vagal-intact or vagotomized, severely hemorrhaged dogs, the MAP and CO increases were attenuated by vagotomy. Blood flow increases in the renal and splanchnic, but not femoral, vascular beds were inhibited by vagotomy. Vagotomy attenuates the hemodynamic response of severely hemorrhaged dogs, limits the effectiveness of isotonic fluid therapy, and exerts a differential effect on blood flow distribution.

Animals↗
PubMed1989

Infertility factors at the Groote Schuur Hospital Fertility Clinic.

Nine hundred and four patients who visited the Fertility Clinic at Groote Schuur Hospital during 1986 were classified according to infertility factors. In 36% of all couples a male factor was present, while 57% had a tubal, 29% an ovulatory, 7% a cervical immunological and 6% a uterine factor. Four per cent of all patients had endometriosis, and 2.4% had unexplained infertility. In 57% of cases only one factor was present, but in the rest between 2 and 5 factors contributed to the infertility of the couple. The study showed that in our population the most common infertility factors are in the male and in women with tubal problems, and resources should be channelled accordingly.

Adult↗
PubMed1988

Autistic spectrum disorders: clinical presentation in preschool children.

It is well recognized that children with "autistic features" constitute a very heterogeneous population. There is a growing consensus that the core symptoms seen in autism include deficits in: (1) social/affective/behavioral functions, (2) developmental language disorders with concomitant deficits in interpersonal communication, and (3) play/preferred activities/preoccupations which have a repetitive or stereotypic quality. The definition of the boundaries of "autism" as opposed to other related pervasive developmental disorders is widely debated among clinicians and research investigators alike. In the present paper, it is argued that autism is a cover term for a spectrum disorder with similarities and differences in the clinical presentation of preschool children. A model for subtyping the autistic spectrum disorders is suggested.

Ammonia↗
PubMed1988

Syndromes in developmental dysphasia and adult aphasia.

We have attempted to draw some parallels between syndromes of adult acquired aphasia and of childhood developmental dysphasia. There appear to be two syndromes that are almost exact duplicates in the adults and the children: (a) pure word deafness and verbal auditory agnosia, and (b) aphemia and verbal dyspraxia. Two other syndromes seem to have rather close but not exact counterparts: Broca's aphasia and the phonologic-syntactic deficit syndrome, and transcortical sensory aphasia and the semantic-pragmatic deficit syndrome. There are two dysphasic syndromes, the phonologic production deficit syndrome and the lexical-syntactic deficit syndrome, that do not seem to have close adult counterparts. Neither of these dysphasic syndromes has been defined in adequate linguistic detail, and it is possible that their description may have to be modified when more data become available. Whether these comparisons between dysphasias and aphasias have heuristic value for guiding external validation studies of the clinically defined dysphasic syndromes of preschool children remains to be determined. Our purpose was to formulate hypotheses as to which cerebral systems are likely to be dysfunctional in children with clinically defined dysphasic syndromes. We recognize that the disorders of language acquisition and those of overlearned adult language have fundamental differences, and that plasticity of the child's developing brain introduces further complexities. Nevertheless, it seems reasonable to think that there are constants in brain organization that span all ages. Looking for language deficits common to aphasic adults (whose lesions can usually be delineated with contemporary neuroimaging techniques) and to dysphasic children (in whom there are rarely any neurologic clues) may be a fruitful way to begin to define the cerebral correlates of the children's deficits.

Adult↗
PubMed1988

Clinical, hematologic, and humoral immune response in female dogs inoculated with Rickettsia rickettsii and Rickettsia montana.

Female Beagles were inoculated intradermally with a sublethal dose of Rickettsia rickettsii and R montana. Three dogs (group 1) were inoculated with 2 X 10(2) plaque-forming units (PFU) of R rickettsia and were treated with tetracycline beginning on postinoculation day (PID) 12; 3 dogs (group 2) were inoculated with 2 X 10(2) PFU of R rickettsii but were not treated; 3 dogs (group 3) were inoculated with 2 X 10(2) PFU of R montana. Group-3 dogs failed to seroconvert and were inoculated a second time on PID 68. Groups 1 and 2 dogs inoculated with R rickettsii became depressed and developed occasional inappetence, fever, hematochezia, and ocular lesions. These dogs had a decrease in PCV and RBC count, an initial decrease in WBC count followed by leukocytosis, and a decrease in platelet count. Group-3 dogs inoculated with R montana remained healthy. After R rickettsii inoculation, the serologic response to spotted fever group (SFG) rickettsial antigens (R rickettsii, R rhipicephali, R montana, and R bellii) was similar. The antibody response to R rickettsii was first detected on PID 9, with peak titers reached by PID 20. Serum titers to R rickettsii remained stable or decreased one dilution through PID 120. Of 4 SFG rickettsial antigens, the highest serologic response was to R rickettsii. A cross-reacting antibody response with R rhipicephali and R montana was nearly identical and was only slightly less than the response to R rickettsii. Cross-reacting antibodies to R belli were of lower mean titer and of shorter duration than were cross-reacting antibodies to other SFG rickettsiae.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Succinate thiokinase in pigeon breast muscle mitochondria.

Succinate thiokinase has been purified from pigeon breast muscle. It has been confirmed that the enzyme is entirely specific for ATP, and Km is very high (approximately 0.8 mM). Activity in mitochondrial sonicates is low enough for it to be doubtful whether the enzyme can support citric acid cycle flux in the tissue. The enzyme appears to have an Mr of 80 000-100 000, and to have two unequal subunits. As determined by SDS gel electrophoresis one subunit certainly has an Mr of 40 000.

Adenosine Triphosphate↗
PubMed1986

Status of pediatric pain control: a comparison of hospital analgesic usage in children and adults.

A chart review was conducted of the records of 90 children and 90 adults, randomly selected and matched for sex and diagnosis, to investigate analgesic usage. Four diagnostic categories (hernias, appendectomies, burns, and fractured femurs) at two hospitals were examined. Results revealed that adults received an average of 2.2 doses of narcotics per day, whereas children received 1.1 (P = .0001). Significant differences in dosing were noted between the diagnostic categories. Diagnoses associated with a longer hospital stay showed a greater discrepancy between narcotic usage in children and adults. Hospital differences were also significant (P = .004) with more doses per day administered at the urban hospital than the rural one. Infants and young children were less likely than older children to have narcotics ordered for them, but, if ordered, frequency of administration was similar for all children. Our study demonstrates that children and adults with the same diagnoses are treated differently as regards narcotic administration. Further research is necessary to determine whether these results represent a difference in pain tolerance in children or a lack of recognition of their discomfort.

Adult↗
PubMed1985

An enzyme-linked immunosorbent assay method for the simultaneous measurement of antibody titer to multiple viral, bacterial or protein antigens.

A model enzyme-linked immunosorbent assay (ELISA) system was developed which permits the user to evaluate replicate single sera dilutions of 46 test and control serum samples for the presence of specific antibody against up to eight different antigens in one assay. The system makes use of a transplanting device for the simultaneous transfer of aliquots of independently diluted replicate test samples along with conjugate and substrate from a serum reservoir plate or from a reagent reservoir onto different antigen coated target plates. Kinetically read, raw absorbance data from tests are transmitted to a microcomputer, where absorbance values from all tests are quickly reduced to predicted titer levels by computer analysis. All titer computations involve the use of a single prescribed standard curve for predicting antibody titer against the different antigens. Between assay repeatability of this procedure is high and its potential for replacing a number of different conventional assays for epidemiological studies has been evaluated.

Animals↗
PubMed1984

Factors associated with parents' and professionals' perceptions of infants in an early intervention program.

Mothers and regular intervention home visitors rated temperament characteristics of 39 high risk or developmentally delayed infants (approximately 9 months corrected age). Mothers who reported greater depression rated their infants as less optimal on several temperament dimensions. Similarly, mothers who were single, less educated, or had infants showing greater developmental delay, described their infants' temperament as less satisfactory than did other mothers. These maternal variables also correlated with home visitors' ratings of infant temperament, although the number of significant correlates was fewer. Discrepancies between parent and professional reports were examined. Mothers of infants showing poorer development rated their infants more positively on activity and rhythmicity than did professionals. Higher educated mothers also tended to report higher activity levels for their infants than did the home visitors. Infant activity, as rated by home visitors, is highly correlated with infant's developmental status. Perhaps mothers of poorly developing infants and those with greater education overestimate infant activity because they have relatively greater difficulty accepting the extent of their infants' functional limitations.

Adult↗
PubMed1984

A developmental study of temporal duration judgments.

First, third, fifth, and seventh graders and college students (18 per grade) made four serial reproductions of each of three time intervals, 8, 13, and 32 sec. The results paralleled those of other studies using only adults since both the psychophysical function and the Weber fraction were typical, and magnitude of judgments was an increasing, negatively accelerated function of trials. None of these effects was a function of age nor were there any age effects in an analysis of variable errors. Analysis of first-degree sequential dependency of judgments (using lag correlations) revealed a slight negative recency which was also invariant with age of Ss.

Adult↗