Search PubMed⌕ Search

Biomedical subjects

D J Harris

Publications and source records attributed to D J Harris.

At least 109 records · Page 6Linked to original sources
PubMed1981

Propionyl coenzyme A carboxylase deficiency presenting as non-ketotic hyperglycinaemia.

A 4-month-old girl presented with myoclonic seizures and an electroencephalogram showing hypsarrhythmia. Hyperglycinuria and a cerebrospinal fluid to plasma glycine ratio of 0.2 suggested the diagnosis of non-ketotic hyperglycinaemia. Propionic acid and methyl citric acid were present in the urine, and propionyl coenzyme A carboxylase was deficient in leucocytes and fibroblasts. The ketotic and non-ketotic hyperglycinaemias cannot be differentiated by CSF: plasma glycine ratios.

Carboxy-Lyases↗
PubMed1981

Sonographic transducer performance cannot be evaluated with clinical images.

A wide variety of in vitro tests, some too sophisticated to perform in a clinical setting, is available to provide information on the performance of sonographic transducers. However, it is a common belief among many clinicians that clinically generated in vivo images are a necessary and sufficient test of sonographic image quality. In order to examine the sensitivity and reliability of quality judgments made from clinical images, some transducers that failed elaborate in vitro tests were used to create clinical scans. In a discrimination test between clinical images created by normal and abnormal transducers, a panel of experienced sonographers was unable to consistently identify scans made by transducers with major flaws in the beam uniformity when the defect occurred only in the near field. The study confirms that rigorous in vitro tests provide unique information on transducer performance and can reveal performance flaws that are overlooked in routine clinical images.

Humans↗
PubMed1981

Mucolipidosis I (acid neuraminidase deficiency). Three cases and delineation of the variability of the phenotype.

Isolated deficiency of the lysosomal hydrolase acid neuraminidase results in multisystem storage of sialic acid-rich oligosaccharides. Wide phenotypic diversity occurs within this biochemical defect. We studied three cases of an infantile form of mucolipidosis I in which the phenotype is dominated by severe Hurloid features. These patients excreted excessive amounts of sialic acid-rich oligosaccharides in their urine, and storage of similar compounds was shown in tissues and cultured fibroblasts. Cultured fibroblasts demonstrated an isolated deficiency of acid neuraminidase; beta-galactosidase levels were normal.

Child↗
PubMed1980

Dominantly inherited macular dystrophy with flecks (Stargardt).

A family had dominantly inherited macular dystrophy with flecks and without evidence of major cone dysfunction. This family shows that the clinical picture of Stargardt's disease can result from at least two different genes: one with dominant and another with recessive heredity. Some patients had fundus flavimaculatus flecks of Stargardt's disease; others did not. In our opinion progressive atrophic macular (foveal) dystrophy as Stargardt's disease without flecks is not a separate clinical entity but part of the same genetic defect. Furthermore, a dominant hereditary pattern in patients without flecks or major cone dysfunction is insufficient evidence for classification of such patients as having cone dystrophy.

Adolescent↗
PubMed1980

Holoprosencephaly and endocrine dysgenesis in brothers.

We report 2 brothers with holoprosencephaly, endocrine dysgenesis, and micropenis. This combination has been reported once previously in sibs (2 sisters) by Hintz et al (1968). In that case, autosomal recessive inheritance may have been the cause. The same may be true in our patients, but X-linked recessive inheritance is not excluded.

Abnormalities, Multiple↗
PubMed1980

Physical factors influencing numerical echo-amplitude data extracted from B-scan ultrasound images.

The replacement of analog-scan converters by digital-scan converters in commercially available B-scan ultrasound equipment provides easily available numerical echo-amplitude data from regions or organs of interest, once the image has been created. These values vary with, and are influenced by, a variety of physical variables, including transducer power output, time-gain compensation, signal threshold, preprocessing digital signal level assignment, frequency, and acoustic beam width. Unless vigorous efforts are made to standardize these variables, clinical reports using numerical analysis as disease descriptors should be viewed critically.

Acoustics↗
PubMed1980

Sonographic tissue texture: influence of transducer focusing pattern.

The ultrasonic beam profile pattern is not accurately known for most transducers in clinical use. A simple scan of an easily available phantom permits the clinician to determine the focusing pattern of his own transducer and equipment. Disregarding other operator-controllable parameters such as the time-gain compensation, output, and system sensitivity, the true echo pattern of a tissue is not accurately represented until the distance of the region of narrowest beam focus is reached. The fine speckled echo pattern commonly seen in uniform organs near the transducer is largely artifactual due to interference phenomena in the near field of the acoustic beam. Closest approximation of true texture is not displayed until near the depth at which the narrowest focus occurs. Beyond that depth, broad, coarser patterns can be expected.

Humans↗
PubMed1980

Dysautonomia in an infant with secondary hyperammonemia due to propionyl coenzyme A carboxylase deficiency.

A male infant who had vomiting and coma in the absence of ketoacidosis was initially thought to have dysautonomia because of abnormal responses to methacholine and histamine, as well as abnormal urinary catecholamine excretion. Following an episode of hyperammonemia, a liver biopsy was performed which revealed a partial deficiency of carbamyl phosphate synthetase activity. The patient was treated with a protein-restricted diet supplemented with a mixture of ketoacid analogues of the essential amino acids, which precipitated ketosis and acidosis. A primary deficiency of propionyl coenzyme A (CoA) carboxylase was subsequently demonstrated. Because disorders of propionate metabolism may not initially present with ketoacidosis, we recommend examination of both plasma and urine for metabolites of this pathway, as well as direct measurement of propionyl CoA carboxylase activity in peripheral blood leukocytes, before performing a liver biopsy to evaluate urea cycle enzyme activities, and particularly before adding keto acid/amino acid mixtures to a protein-restricted diet.

Acyl Coenzyme A↗
PubMed1979

Reproductive risk of t(13q14q) carriers: case report and review.

We report a four-generation kindred with a balanced 13q14q Robertsonian translocation. The proband had the Down sydrome, due to trisomy of chromosome 21; he also carried the balanced D-group translocation. S segregation analysis of 86 sibships was performed to examine the risk of t(13q14q) carrier parents having trisomy 21, 47,XXY, or trisomy 13 children by which a number of families were ascertained. None of these disorders recurred after birth of the propositi. The frequency of abortions was not different from that of the general population. The conditional segregation ratio for balanced translocation carriers among the phenotypically normal offspring of carrier parents was 0.55 +/- 0.04.

Abortion, Spontaneous↗
PubMed1979

Hyperbaric hyperreflexia: tendon-jerk and Hoffmann reflexes in man at 43 bars.

Tendon jerk (TJR) and Hoffmann (H) reflexes of the soleus muscle were studied in two men during a 26-day simulated oxygenhelium dive to a maximum pressure of 43 bars. The amplitude of the TJR response was observed to increase markedly after compression and also at the end of decompression. This biphasic pattern of enhanced reflectivity was reproduced by synchronised but much smaller variations in H reflex response. The positive facilitatory effects of applying Jenkdrassik's manoeuvre were reduced and the negative effects increased during hyperbaric exposure. Excitability cycles (twin-pulses methods) revealed modifications in one subject similar to those observed in clinical hyperreflexia, namely a shortening of Phase III and an enhancement of Phase IV. The other subject exhibited a notable depression of Phase IV. Abnormal EMG recordings are described including randomly-triggered slow wave potentials with no mechanical effects, and fixed, long latency late responses of a reflex nature with a definite mechanical effect. The contention that alterations in vestibulo-spinal relations may result in the release from tonic presynaptic inhibitory control of myotatic reflex arc excitability is discussed as a partial explanation for these and related findings.

Adult↗
PubMed1979

Observations on the knee-jerk reflex in oxygen-helium at 31 and 43 bars.

Sensitivity of the knee-jerk reflex was measured in three men during two experimental saturation dives, a fast compression dive to 300 msw and a slow compression dive to 420 msw. In all cases, the force produced at the ankle by the reflex (isometric) contraction was augmented after compression. The most marked increases were observed during the shallower but faster compression dive. During decompression, reflex sensitivity remained enhanced during the 300-m dive but returned to control levels during the 420-m dive. Furthermore, the usual facilitatory effects of Jendrassik's maneuver were abolished during the 300-m dive. Peripheral nerve conduction velocity and synaptic delay apparently remained unaffected. The conclusion that the observed hyper-reflexivity results from supra-spinal influence on alpha-motor-neuron excitability and possibly on gamma-efferent activity is discussed in relation to other reflex studies in hyperbaric O2-He and O2-N2 environments.

Adult↗