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Biomedical subjects

T McKenzie

Publications and source records attributed to T McKenzie.

18 recordsLinked to original sources

A community health promotion partnership model: the South Carolina health connection.

Over a five year period, the South Carolina Health Connection Project has evolved to multi-site, multi-organization community-base collaborative initiative. From this project over $60,000.00 in funds have been secured. However, when costing the human resources and many other in-kind contributions involved in the SCHC Projects activities, the Project can modestly be valued at nearly $200,000.00. The efforts of a few have been shared with others, who also shared the resources with others, and the health promotion empowerment cycle continues. We believe the South Carolina Health Connection is an exemplary of a Community Health Promotion Partnership Model. We hope you will agree!

Adolescent↗

Diclofenac hepatitis.

We report five cases of biopsy-proven hepatitis developing between six and 20 weeks after administration of diclofenac. In one patient jaundice had previously developed following use of ibuprofen. In another the clinical, biochemical and histopathological features were those of chronic active hepatitis and treatment with corticosteroids was required. All patients recovered from their liver injury without sequelae. Resolution of symptoms occurred between three and 12 weeks following cessation of the drug, while liver function tests returned to normal between seven and 16 weeks after drug withdrawal, except in the patient with chronic active hepatitis who remained biochemically abnormal for eight months. Three of the five patients developed transient circulating autoantibodies, suggesting immune mechanisms may be important in the pathogenesis of this injury. The incidence of severe hepatic dysfunction related to the use of diclofenac appears low and is probably in the order of one case per 50-100,000 prescriptions.

Aged↗

In vitro type II binding of chromosomal DNA to membrane in Bacillus subtilis.

DNA-membrane association critical for initiation of DNA replication in Bacillus subtilis can be classified into two types. Type I is salt resistant and dependent on the initiation gene, dnaB, and type II is salt sensitive and independent of the dnaB gene. We found and sequenced two adjacent areas of type II binding within 1% of oriC on the B. subtilis chromosome.

Amino Acid Sequence↗

Extended spectrum cephalosporins and Clostridium difficile.

There is little information about how commonly the newer cephalosporins cause diarrhoea due to Clostridium difficile. In this study of 111 patients with C. difficile-associated diarrhoea, 106 had received antimicrobial agents in the four weeks before detection of C. difficile. The relative risk for each antimicrobial agent was greatest with clindamycin, followed by cefotaxime, cephamandole and ceftriaxone. There was no statistically significant difference in risk between the cephalosporins evaluated. Narrower spectrum penicillins, anti-pseudomonal penicillins and aminoglycosides were not potent inciting agents.

Cephalosporins↗

Nucleotide sequence of Bacillus subtilis dnaB: a gene essential for DNA replication initiation and membrane attachment.

The complete nucleotide sequence of the Bacillus subtilis dnaB gene and its flanking regions was determined. The dnaB gene is essential for both replication initiation and membrane attachment of the origin region of the chromosome and plasmid pUB110. It has been known that there are two different classes (dnaBI and dnaBII) in the dnaB mutants; dnaBI is essential for both chromosome and pUB110 replication, whereas dnaBII is necessary only for chromosome replication. The nucleotide sequence revealed that dnaBI and dnaBII are two functional domains in the single dnaB gene. The mutation sites of two mutants, belonging to dnaBI and dnaBII, respectively, were also determined as substitutions of amino acids. The putative DnaB protein deduced from nucleotide sequence consists of 472 amino acids (55 kDa) with no cysteine residue. A 55-kDa polypeptide produced in an in vitro transcription-translation system was labeled with [35S]methionine but not with [35S]cysteine. The DnaB protein has a highly hydrophobic sequence of 20 amino acids in its N-terminal region, a possible DNA binding site, and two possible ATP binding sites. The dnaBI domain is between the DNA binding site and one of the ATP binding sites; the dnaBII domain is close to the other ATP binding site. Comparison of the amino acid sequence between the "dnaB protein" and those of other dna genes of Escherichia coli showed no homology, suggesting that the dnaB gene of B. subtilis may be analogous to a hitherto undiscovered gene in E. coli.

Amino Acid Sequence↗

The nucleotide sequence of pUB110: some salient features in relation to replication and its regulation.

For the study of DNA-membrane interaction and the regulation of replication initiation we have determined the total nucleotide sequence of pUB110. As previously reported, this plasmid replicates in B. subtilis at a copy number of 30-50 per cell, with a majority of plasmids (60-80%) bound to the membrane (type-I binding). The type-I membrane binding is apparently necessary for pUB110 initiation of replication in vivo, but the membrane binding site is not known. Furthermore, four areas of the plasmid specifically bind to Bacillus subtilis membrane in an in vitro binding reaction (type II binding). These two types of membrane binding of pUB110 are different in that the in vivo binding (type-I) requires one (dnaBI) of the host initiation genes and is high-salt resistant, whereas the in vitro binding (type-II) does not require the dnaBI gene product and is high-salt sensitive. 7-mer double-strand sequence, TCAGCAA/AGTCGTT, or one-base derivatives of this sequence are frequently (17 of 23 of the 7-mer sequences) found in or close to the type-II binding areas. One of them is found at a restriction enzyme recognition site of a binding area that destroys the type-II membrane binding. These sequences may or may not have significance in type-II membrane binding. In addition to the neomycin resistance gene, the sequence data indicate two sizable open reading frames, ORF alpha and ORF beta, and two small ORF, gamma, and delta. All of these reading frames are in the same direction, which coincides with the direction of the replication. The open reading frame alpha (ORF alpha) corresponding to 334 amino acids close to the replication origin may be essential for the initiation of replication of PUB110. The putative protein alpha corresponding to this open reading frame contains a consensus sequence of the DNA binding sites which are found in a number of known DNA-binding proteins. The consensus DNA binding site of protein alpha is flanked by two hydrophobic areas. These two observations suggest that the corresponding protein may have both an affinity to a specific site in pUB110, and an affinity to the membrane.

Bacillus subtilis↗

Isolation of a thermostable enzyme variant by cloning and selection in a thermophile.

We developed a method for rapidly generating thermostable enzyme variants. Our strategy is to introduce the gene coding for a given enzyme from a mesophilic organism into a thermophile, Bacillus stearothermophilus. Variants that retain the enzymatic activity at the higher growth temperatures of the thermophile are then selected. This strategy was applied to kanamycin nucleotidyltransferase, which confers resistance to the antibiotic kanamycin. B. stearothermophilus carrying the wild-type enzyme is resistant to the antibiotic at 47 degrees C but not at 55 degrees C and above. Variants that were kanamycin resistant at 63 degrees C were obtained by selection of spontaneous mutants, by passage of a shuttle plasmid through the Escherichia coli mutD5 mutator strain and introduction into B. stearothermophilus by transformation, and by growing the thermophile in a chemostat. The kanamycin nucleotidyltransferases purified from these variants were all more resistant to irreversible thermal inactivation than is the wild-type enzyme, and all have the same single amino acid replacement, aspartate to tyrosine at position 80. Mutants that are even more heat stable were derived from the first variant by selecting for kanamycin resistance at 70 degrees C, and these carry the additional change of threonine to lysine at position 130. This strategy is applicable to other enzymatic activities that are selectable in thermophiles or that can be screened for by plate assays.

Bacillus subtilis↗

Dopaminergic regulation of natriuretic response to acute volume expansion in dogs.

Effects of carbidopa, a dopa (3,4-dihydroxyphenylamine) decarboxylase inhibitor, on the renal, haemodynamic and hormonal responses to acute volume expansion were examined in six healthy mongrel dogs which were infused intravenously with 0.9% sodium chloride solution (saline; 30 ml h-1 kg-1) over 2 h. Saline infusion studies were performed in the absence (control) and in the presence of carbidopa given by nasogastric tube in a dose of 1 mg/kg every 8 h beginning 24 h before the infusion. Saline infusion resulted in an increase in renal excretion of dopamine (3,4-dihydroxyphenylethylamine) and a decrease in renal excretion of noradrenaline. Carbidopa treatment decreased urinary sodium excretion and eliminated the increase in renal production of dopamine in response to saline infusion without affecting renal or haemodynamic response to acute vascular volume expansion with saline. Carbidopa treatment obliterated the suppression of aldosterone produced by saline infusion. Thus, dopamine appears to play a significant role in mediating both the natriuretic and aldosterone response to acute volume expansion.

Aldosterone↗

Effects of light-deprivation on development of photopositive behavior in Xenopus laevis tadpoles.

The development of amphibian sensory systems and behavior is generally considered to proceed normally without reference to sensory experience during embryonic or larval stages. Most of the supporting research, however, has concentrated on the retinotectal (visual) systems of anurans and has ignored behaviors directed by other sensory systems. We demonstrate that early exposure to light is necessary for the development of photopositive behavior in Xenopus laevis tadpoles, a behavior probably directed by the pineal complex. Light-deprivation during the tadpoles' first 10 days of development results in a long-lasting reduction in the tadpoles' light preference. The development of a strong light preference is not influenced by light-deprivation before the tadpoles are 2 days old or after the tadpoles are 10 days old, but light-deprived tadpoles recover a weak light preference after subsequent days of rearing in the light. Lengthening the tadpoles' exposure to light during the first 10 days of development produces increasingly strong light preferences. Considering the important role of the pineal complex in guiding phototactic behaviors in anurans, we suggest that light-deprivation alters photopositive behavior in Xenopus tadpoles by altering the development of the pineal complex.

Animals↗

Brain scan as an aid in the diagnosis of acoustic neuroma recurrence.

Brain scans using 99Tcm were performed on 34 patients from whom acoustic neuroma had been removed. The age range was 19 to 66 years at the time of operation. The scans were carried out at intervals up to 13 years postoperatively. There were 4 positive. 3 doubtful, and 26 negative scans. A policy is formulated for periodic scanning as an integral part of the follow-up programme of acoustic neuroma patients.

Adult↗

Occult intrasacral meningocoele.

A case is reported of the rare lesion occult intrasacral meningocoele in a 27-year-old woman who developed symptoms for the first time shortly after the birth of her fourth child. The terminology of the condition is discussed and its pathogenesis, mode of presentation, and treatment reviewed.

Adult↗