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Biomedical subjects

J Hall

Publications and source records attributed to J Hall.

At least 19 recordsLinked to original sources
PubMed1992

The use of chimeric gene constructs to express a bacterial endoglucanase in mammalian cells.

The synthesis and secretion of a truncated Clostridium thermocellum endoglucanase (EGE') encoded by the celE' gene was investigated in Chinese hamster ovary (CHO) cells. Fusion genes consisting of the human growth hormone (hGH) gene and celE', transcribed from the SV40 early enhancer/promoter, were constructed and stably transfected into CHO cells. A gene consisting of celE' inserted into the first exon of the hGH gene resulted in the synthesis of truncated proteins (less than or equal to 22 kDa) lacking endoglucanase activity. Cloning celE' into the second exon of the hGH gene, resulted in the synthesis and secretion of a 50 kDa protein with endoglucanase activity. A 50 kDa protein was also synthesised by cells transfected with celE' cloned into the fifth exon of the hGH gene. However, despite a 5-fold increase in enzyme activity compared to the exon 2 transfected cell line less than 40% of the protein was secreted. Constructs devoid of introns, in which celE' was fused to the SV40 early promoter and to the rabbit beta-globin polyadenylation sequence resulted in a 2-18-fold increase in endoglucanase activity compared to the constructs containing introns. In addition more than 75% of the synthesised protein was secreted. Analyses of EGE' encoded mRNA from the transfected cell lines suggests that the presence of introns results in the aberrant splicing of message by the use of cryptic splice sites in the celE' gene. These results demonstrate that introns are not required for the efficient expression of a bacterial endoglucanase in mammalian cells, rather introns appear to reduce expression of the encoded protein.

Amino Acid Sequence↗
PubMed1992

Lack of effects of selenium on N-nitrosomethylbenzylamine-induced tumorigenesis, DNA methylation, and oncogene expression in rats and mice.

The effects of dietary selenium deficiency and excess on N-nitrosomethylbenzylamine-(NMBA) induced esophageal neoplasia in rats and forestomach tumors in mice and the effects of dietary selenium on DNA adduct formation and on the activities of DNA adduct-repairing enzyme and oncogene expression in rat esophagus were investigated. The esophageal and forestomach tumors were induced by administration of NMBA by gavage with a total dose of 39 mg/kg body wt in rats and 12 mg/kg body wt in mice. Neither selenium dietary deficiency (Se < 0.02 ppm) nor selenium excess (2.0 ppm) showed any significant effect on the incidence of tumors or number of tumors per tumor-bearing animal. For the DNA adduct formation studies, rats were given a dose of NMBA intraperitoneally after six weeks on the different selenium-containing diets. No significant difference in the amount of the DNA adduct O6-methyldeoxyguanosine was found among the different selenium-treated groups. In a parallel group of rats that did not receive NMBA, the levels of esophageal O6-methyldeoxyguanosine DNA methyltransferase were not significantly altered by dietary selenium levels. The c-myc oncogene expression in rat esophagus was induced by the administration of NMBA (3 mg/kg body wt) by gavage once a week for eight weeks. Dietary selenium did not show any effects on its expression. On the basis of the results of these studies, dietary selenium has no effects in the NMBA-induced tumor model.

Animals↗
PubMed1992

Accuracy of a portable interpretive ECG machine in diagnosis of acute evolving myocardial infarction.

From a study of 526 patients having automatic ECG analysis, criteria were established which diagnosed acute evolving Q wave myocardial infarction with 71% sensitivity and 98% specificity. Specificity was 100% when patients with known previous Q wave infarction were excluded. In pre-hospital practice the high sensitivity and specificity were maintained. This method appears appropriate, when other criteria are met, for paramedic-initiated pre-hospital thrombolysis with remote supervision of a cardiologist by telephone.

Adult↗
PubMed1992

The rationing of health care: should Oregon be transported to Australia?

The Oregon Plan is an ambitious attempt to address the widespread problem in the United States of a growing number of individuals who are without private health insurance and are not eligible for federal assistance programs. Its aim is to provide universal access for all Oregonians, without increasing total health care expenditure, by restricting the cover of some treatments. It has aroused interest in Australia and elsewhere. The appeal of the Oregon Plan lies in its explicit approach to rationing, in community participation in setting priorities, and the use of a cost-effectiveness framework. This paper describes the beginnings and the development of the Oregon Plan, and compares the actual development of the Plan with the rhetoric. There is a gap between the rhetoric of the Plan and its reality. The Oregon plan should be considered in the context of the United States health care system. We compare the American problems with those facing the Australian health care system and conclude that the answer to the question of whether Oregon should be transported to Australia is no. Nevertheless there are elements of the rhetoric of the Plan which could be applied in rationing health care in Australia.

Health Care Rationing↗
PubMed1992

Predisposition to and late onset of upper airway obstruction following angiotensin-converting enzyme inhibitor therapy.

Angioedema of the face and neck is a rare but potentially fatal complication of angiotensin-converting enzyme inhibitor (ACEI) use. We retrospectively reviewed five cases of ACEI angioedema seen at our institution over the past 2 1/2 years. Four of the cases occurred with enalapril and one with lisinopril. Onset of symptoms varied from two days to ten months. Importantly, three of the five patients had been receiving medication three months or longer, suggesting clinicians must consider this complication during long-term administration of these agents. Three of the five patients were markedly obese, had a history of previous face and neck surgery, or had been intubated in the past. Thus, we propose that previous manipulation or trauma of the upper airway, perhaps resulting in airway narrowing, may represent a risk factor for upper airway obstruction secondary to ACEI-induced angioedema.

Adult↗
PubMed1992

Keratitis in free-ranging koalas (Phascolarctos cinereus) on Magnetic Island, Townsville.

Seventy free-ranging koalas (Phascolarctos cinereus) from Magnetic Island (Queensland, Australia) underwent an ocular examination, blood collection and serological examination for Chlamydia psittaci antibodies, and an examination of their teeth and genitalia. In 12 koalas long-standing unilateral keratitis was noted and in another 10 animals long-standing bilateral keratitis was observed. All animals were seronegative for Chlamydia psittaci and apart from some nasal discharge and a variety of assorted medical findings there was no sign of chlamydial infection. These ocular findings probably represent a new disease of unknown etiology.

Animals↗
PubMed1990

Endoglucanase E, produced at high level in Escherichia coli as a lacZ' fusion protein, is part of the Clostridium thermocellum cellulosome.

The Clostridium thermocellum celE gene was expressed at high level in Escherichia coli TG1 when placed under the transcriptional and translational control of lacZ' in pUC18; in the presence of a multicopy plasmid (pNM52) containing the lacIq gene, expression of full-length and truncated forms of celE was regulated by isopropyl-beta-D-thiogalactopyranoside. Catalytically active endoglucanase E (EGE) produced by E. coli was subject to proteolytic processing. The main protein species produced from full-length and truncated forms of celE was around 40 kDa in size and had an N-terminal amino acid sequence corresponding to that derived for mature EGE from the nucleotide sequence; in addition, larger species of about 75 kDa, presumably corresponding to full-size EGE, were produced by E. coli containing the full-length celE gene. Even after removal of the signal peptide sequence, EGE produced by E. coli was secreted into the periplasm. Up to 157 bp could be deleted from the 5' end of the celE gene without affecting the catalytic activity of EGE produced by E. coli. A polypeptide of Mr 86 kDa, immunoreactive with anti-EGE antiserum, was demonstrated in the high-molecular-weight, cellulose-binding multiprotein aggregate recoverable from C. thermocellum culture supernatant.

Amino Acid Sequence↗
PubMed1979

A new acoustic reflex pattern.

A new crossed-vs-uncrossed acoustic reflex pattern has been observed in four patients with retrocochlear disorder. The new reflex pattern is characterized by a unique "uni-box" configuration. Reflexes are abnormal with sound to the affected ear on crossed stimulation only. In one additional patient, a variation of the uni-box pattern was found on suprathreshold reflex amplitude measures. WE observed a large ear difference between reflex amplitude functions in the crossed condition, but not in the uncrossed condition. This observation suggests that reflex amplitude measures may be a valuable addition to threshold measures in some patients.

Adolescent↗
PubMed1979

Septicemia caused by Pseudomonas paucimobilis.

A case of septicemia caused by Pseudomonas paucimobilis is reported. This represents the first definitive case of disease produced by this yellow-pigmented, nonfermentative bacillus.

Aged↗
PubMed1979

Lymphocyte recirculation and the gut: the cellular basis of humoral immunity in the intestine.

During the last 15 years evidence has accumulated which shows that the B immunoblasts generated in the gut associated lymphoid tissue (GALT) in response to antigenic stimuli from the intestinal tract are discharged into the intestinal lymph. The lymph stream carries them to the blood but most of them soon extravasate in the gut (and some other mucosae) and develop into plasma cells which synthesise secretory immunoglobulins. In sheep, there is some evidence that these cells may be derived initially from a sub-set of small lymphocytes which circulate preferentially through the GALT, but the situation in rodents is less clear. However, in most species it is becoming clear that although some of the antibodies produced by the sub-mucosal plasma cells are secreted directly into the lumen of the gut many find their way, via the lymph, into the blood and, if in the form of polymeric IgA, they are rapidly and actively transported by the hepatocytes into the bile and thus gain direct access to the duodenum in concert with the entry of freshly ingested food and bacteria.

Animals↗
PubMed1978

Rapid active transport of immunoglobulin A from blood to bile.

Immunoglobulins were isolated from the serum or ascitic fluid of Lou/Wsl rats bearing plasmacytomas and labeled with 125I. When labeled IgA was injected i.v. it disappeared from the blood serum much more rapidly than IgG2 so that after 3 h less than 10% remained. This rapid disappearance of the injected IgA was not seen in rats with ligated bile ducts. In rats with cannulated bile ducts, the labeled IgA appeared rapidly in the bile so that 25% of the injected dose was recovered in 3 h; at the peak of this biliary excretion the specific radioactivity of the bile (cpm/milligram protein) was about 200 times greater than that of the blood serum. Thus much of the IgA which finds its way into the blood is rapidly and actively transported across the liver so that it enters the gut lumen via the biliary tract.

Animals↗
PubMed1978

Long term post-traumatic retrograde corticospinal degeneration in man.

The spinal cord and brain of a man who died 18 years after a crush injury of lumbar segments contained some unusual lesions. There was a reduced number of myelinated axons in the corticospinal tracts as high as the fifth cervical segment. Such retrograde degeneration has been described in human pyramidal tracts only a few times. The results of reported studies of experimental retrograde degeneration have been inconsistent. The course of the fasciculus gracilis, as delineated by gliosis, was atypical, and an unusual glial nodule, possibly neoplastic, was present in the dorsal columns at C8.

Accidents, Traffic↗