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Biomedical subjects

A Hill

Publications and source records attributed to A Hill.

At least 253 records · Page 14Linked to original sources
PubMed1984

Primary biliary cirrhosis, dark adaptometry, electro-oculography, and vitamin A state.

Twenty five patients with primary biliary cirrhosis were studied for vitamin A state. In nine patients found to have low circulating vitamin A concentrations no abnormality was found on electro-oculography or in dark adaptation. A positive correlation was found between retinol binding protein and vitamin A values (r = +0.88; p less than 0.001) and between serum albumin and vitamin A values (r = +0.75; p less than 0.001). A weaker and negative correlation was found between serum bilirubin (r = -0.47; p less than 0.05) and vitamin A values. Patients with primary biliary cirrhosis should not receive regular parenteral or even oral vitamin A supplementation unless dark adaptometry or electrooculography yields an abnormal result.

Dark Adaptation↗
PubMed1984

Two mouse early embryonic beta-globin gene sequences. Evolution of the nonadult beta-globins.

We have determined the complete nucleotide sequence of two early embryonic beta-globin genes of the BALB/c mouse: beta h0 and beta h1 X beta h1 codes for the embryonic z protein, while the beta h0 gene may be a minor early embryonic beta-globin gene. The general sequence organization of both genes is entirely analogous to other functional globin genes. There is, however, a 220-base pair insertion of unique sequence within the first intron of beta h0 X beta h0 and beta h1 are 96% homologous for 260 base pairs 5' to the AUG initiation codon, and 93% homologous throughout their coding regions. Analysis of the 5'-flanking sequence demonstrates that these genes are more nonadult-like than adult-like. The sequences show evidence for gene conversions among the mouse nonadult beta-globin genes that were limited to individual exons, presumably by the presence of non-homologous introns. We propose that this arrangement has the beneficial evolutionary effect of allowing gene conversion to act independently on regions of the protein with different structural or functional responsibilities. beta h0 and beta h1 are evolutionary homologs to the human fetal and rabbit beta 3 genes, while their manner of expression is similar to rabbit beta 3 and dissimilar to human fetal expression. The evolutionary history of the human beta-globin genes, therefore, includes the recruitment of an embryonic gene to fetal developmental control.

Animals↗
PubMed1984

Rapidly progressive posthemorrhagic hydrocephalus. Treatment with external ventricular drainage.

Nineteen premature infants with progressive posthemorrhagic hydrocephalus with increased intracranial pressure were treated with external ventricular drainage. Progression of hydrocephalus was arrested during the drainage period in each patient. Three of the 19 infants required no further therapy. Sixteen had recurrence of progressive ventricular dilatation, and all but one eventually had placement of a ventriculoperitoneal shunt, although under more favorable medical conditions than existed at the time of institution of external ventricular drainage. Three of the 19 infants died of causes unrelated to the external ventricular drainage. Of the 16 survivors, seven infants had a developmental quotient or formal IQ of over 75. Outcome was poorest for those infants with accompanying intracerebral hemorrhage. We consider ventriculostomy to be an effective temporizing measure in small infants with rapidly progressive posthemorrhagic hydrocephalus with increased intracranial pressure in whom ventricular decompression is necessary and placement of a ventriculoperitoneal shunt is not feasible.

Catheterization↗
PubMed1984

Molecular cloning and sequence analysis of a cDNA coding for the mouse alpha-like embryonic globin chain x.

Cytoplasmic poly(A)+mRNA from 12-day mouse-yolk-sac erythroid cells has been used to prepare a cDNA library in the plasmid pBR322. One clone containing sequences coding for the alpha-like embryonic globin chain x, pHE52, has been identified by hybrid selection and in vitro translation of the complementary mRNA. The nucleotide sequence of pHE52 confirms that it codes for an embryonic alpha-like globin chain. The insert sequence is 316 nucleotides long, contains the codons corresponding to amino acid residues 43-141, and extends into the 3' untranslated region. An analysis of the nucleotide sequence of pHE52 and the other known alpha globins suggests that the adult-embryonic divergence began approx. 400 million years ago reflecting a difference in the evolutionary history of the alpha- and beta-globin gene complexes.

Amino Acid Sequence↗
PubMed1984

Diagnosis and evolution of periventricular leukomalacia: a study with real-time ultrasound.

Periventricular leukomalacia is an ischemic lesion in periventricular white matter of premature infants. Hemorrhage into the ischemic area occurs in up to 25% of cases. We report two cases in which the diagnosis of periventricular leukomalacia was made during life with real-time ultrasound scanning. In one case, serial scans demonstrated the evolution of echodense regions, observed in the first 3 days of life, to cystic echolucent areas at 4 weeks. In the second case, periventricular echodense areas did not precede the occurrence of cystic echolucent lesions. This may reflect a more chronic ischemic cerebral insult (consistent with recurrent apnea and bradycardia) rather than a presumed acute episode of cerebral ischemia (with or without secondary hemorrhage) sustained by the first case. Real-time ultrasound scanning is a simple, non-invasive technique with which to document the evolution of periventricular leukomalacia, and thus to define the clinical neurological correlates in the neonatal period.

Brain Ischemia↗
PubMed1984

Chromatin conformation of yeast centromeres.

The centromere region of Saccharomyces cerevisiae chromosome III has been replaced by various DNA fragments from the centromere regions of yeast chromosomes III and XI. A 289-base pair centromere (CEN3) sequence can stabilize yeast chromosome III through mitosis and meiosis. The orientation of the centromeric fragments within chromosome III has no effect on the normal mitotic or meiotic behavior of the chromosome. The structural integrity of the centromere region in these genomic substitution strains was examined by mapping nucleolytic cleavage sites within the chromatin DNA. A nuclease-protected centromere core of 220-250 base pairs was evident in all of the genomic substitution strains. The position of the protected region is determined strictly by the centromere DNA sequence. These results indicate that the functional centromere core is contained within 220-250 base pairs of the chromatin DNA that is structurally distinct from the flanking nucleosomal chromatin.

Base Sequence↗
PubMed1984

Congenital hydrocephalus secondary to intra-uterine germinal matrix/intraventricular haemorrhage.

An infant with hydrocephalus which had been diagnosed at birth died at one month of age. Subsequent neuropathological studies demonstrated old germinal matrix haemorrhage and complete occlusion of the aqueduct of Sylvius by fibroglial tissue, both of which appeared to be older than four weeks, indicating that they had occurred in utero. These observations are consistent with the occurrence of intra-uterine intraventricular haemorrhage secondary to haemorrhage of the subependymal germinal matrix, leading to occlusion of the aqueduct of Sylvius and hydrocephalus prior to birth.

Cerebral Aqueduct↗
PubMed1984

Inhibitory substances in horse sera used in the preparation of microbiological culture media.

The failure of N. gonorrhoeae to grow on isolation media was found to be due to inhibitory substances present in commercially available horse sera. Subsequent investigations indicated that the inhibitory action of the horse serum may have been due to antibodies to N. gonorrhoeae, H. influenzae, H. parainfluenzae and beta hemolytic streptococci. This experience highlights the need for media quality control programmes in laboratories which prepare microbiological culture media.

Animals↗
PubMed1984

Cryptosporidiosis in the acquired immune deficiency syndrome.

Cryptosporidiosis was found in a patient with the acquired immune deficiency syndrome. The microbiological and morphological features of this newly recognized opportunistic infection are distinctive and diagnostic.

Acquired Immunodeficiency Syndrome↗
PubMed1984

A potential mechanism of pathogenesis for early posthemorrhagic hydrocephalus in the premature newborn.

Ventricular dilation is common following intraventricular hemorrhage. Neuropathologic studies have demonstrated that chronic posthemorrhagic hydrocephalus most commonly is a result of an obliterative arachnoiditis in the posterior fossa or is due to obstruction of flow of CSF within the ventricular system. Recent use of ultrasound scanning has demonstrated the occurrence of ventricular dilation within days of intraventricular hemorrhage (prior to the expected time of development of arachnoiditis). In the case described, serial real-time ultrasound scans demonstrated small mobile particles within dilated ventricles seven days following intraventricular hemorrhage. There was no obstruction of CSF flow within the ventricular system. Thus, in this case, ventricular dilation may have been secondary to plugging of arachnoid villi by the small particulate matter and, as a consequence, decrease in CSF reabsorption.

Cerebral Hemorrhage↗
PubMed1983

125I Radioimmunoassay of serum ursodeoxycholyl conjugates.

A radioimmunoassay for serum ursodeoxycholic conjugates using a 125iodine ligand has been developed. The bile acid was present in normal fasting serum (0.19 +/- SD 0.19 mumol/l, n = 24) and 2-hour post-prandial serum (0.8 +/- SD 0.8 mumol/l, n = 16). Gallstone patients undergoing oral ursodeoxycholic acid therapy had significantly higher post-prandial serum levels (21.5 +/- SD 14.0 mumol/l, n = 15) by radioimmunoassay. Gas liquid chromatography analysis indicated that in normal serum ursodeoxycholic acid was totally conjugated, whereas sera from gallstone patients contained a proportion as the free bile acid (10.2 +/- SD 8.1 mumol/l, n = 15). Following an oral dose of ursodeoxycholic acid, both unconjugated and conjugated forms of the bile acid appeared in the serum of healthy individuals.

Bile Acids and Salts↗
PubMed1983

Hypoxic/ischaemic cerebral injury in the neonatal brain. A report of sonographic features with computed tomographic correlation.

Ultrasound has been used in 11 neonates whose history or clinical features suggested the possibility of hypoxic/ischaemic lesions. The ultrasound findings were correlated with computed tomographic findings in nine infants and with pathological findings in two. On ultrasound scan, areas of increased echoes represented both hypoxic/ischaemic and haemorrhagic lesions. However, the distinction between them could not be made with certainty. Cystic changes were shown clearly by ultrasound as were cerebral vascular pulsations in and adjacent to the areas of increased echoes. With computed tomography, hypoxic/ischaemic lesions were represented by areas of decreased density and haemorrhagic lesions by areas of increased density. Computed tomography failed to clearly demonstrate the cystic changes. Three types of lesions, viz. diffuse, focal and periventricular were based on the location of brain injury, the former two occurring in term infants and the latter in premature infants. Ultrasound has been shown to be of value for definition of the site and extent of hypoxic/ischaemic cerebral lesions in the newborn and for observation of their evolution.

Brain Ischemia↗
PubMed1983

Ventricular dilation following intraventricular hemorrhage in the premature infant.

Periventricular/intraventricular hemorrhage occurs commonly in the premature newborn. Recent studies indicate an incidence of 35-45%. Following PVH/IVH, the likelihood of developing hydrocephalus is related to the severity of the hemorrhagic lesion. Ventricular dilation may be due to an obliterative arachnoiditis affecting principally the posterior fossa or, less commonly, due to obstruction of flow of cerebrospinal fluid within the ventricular system by clots or other debris. With moderate to severe hemorrhagic lesions, ventricular dilation may occur at the time of PVH/IVH. More commonly, progressive dilation begins one to three weeks following PVH/IVH. The classical signs of hydrocephalus, ie. bulging of anterior fontanelle and inappropriate increase in head circumference, may not appear for days to weeks following onset of ventricular dilation. The precise significance of such normal-pressure hydrocephalus in the genesis of brain injury in the newborn is unknown. Following diagnosis of PVH/IVH, close surveillance of ventricular size with ultrasound scans is indicated. When there is slowly progressive ventricular dilation with normal intracranial pressure, the choice of therapy is made difficult because of frequent spontaneous arrest in such cases. Several modes of therapy have been reported including drugs to decrease the formation of cerebrospinal fluid and the use of serial lumbar punctures. When ventricular dilation is rapid with intracranial hypertension, ventricular drainage is indicated.

Arachnoiditis↗