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Biomedical subjects

R Johnston

Publications and source records attributed to R Johnston.

At least 73 records · Page 4Linked to original sources
PubMed1992

Elevation of the medical plateau of the tibia in the treatment of Blount disease.

Seven children, between ten and thirteen years old, had elevation of the medial plateau of the tibia for correction of severe varus deformity secondary to Blount disease. The deformity was severe (grade V or VI according to the system of Langenskiöld and Riska) in all patients; the average preoperative varus deformity, determined by the angle formed by the femoral shaft and the tibial shaft, was 25 degrees. The goal of the operation was restoration of a more normal configuration of the articular surface of the proximal end of the tibia. This was accomplished by direct elevation of the depressed medial tibial plateau. All patients had an osteotomy to correct the alignment of the tibia. The osteotomy was performed concomitant with the elevation of the plateau in three patients, before the elevation in three, and after the elevation in one patient. Four patients had a concomitant osteotomy of the femur to align the knee joint parallel to the floor. The results were good in five patients and fair in two.

Child↗
PubMed1991

The entire nucleotide sequence of foxtail mosaic virus RNA.

The nucleotide sequence of the RNA genome of foxtail mosaic virus (FMV), a member of the potexvirus family, is 6151 nucleotides long, exclusive of a poly(A) tail. The RNA contains five principal open reading frames (ORFs), designated from the 5' terminus as encoding proteins with Mr values of 152.3K (ORF1), 26.4K (ORF2) which overlaps an 11.3K (ORF3) product, 5.8K (ORF4) which overlaps a 28.8K readthrough protein (ORF5A) which leads into the coat protein cistron of 23.7K (ORF5). The sizes and composition of the proteins encoded by the ORFs are generally similar to those found in other potexviruses; the least similar is the coat protein which nonetheless retains apparently critical consensus regions. The 5' terminus of the previously reported 0.9 kb subgenomic (sg) RNA was determined by S1 nuclease mapping and shown to begin with the sequence GAAGA, 43 nucleotides upstream from the first nucleotide of the coat protein initiation codon. The positions of the 5' end of this sgRNA and of that deduced from the nucleotide sequence for a 1.9 kb sgRNA are entirely consistent with the previously published sizes of these sgRNAs.

Amino Acid Sequence↗
PubMed1990

Double giant fusiform aneurysms of the posterior cerebral artery.

Subarachnoid hemorrhage in a patient with two giant fusiform aneurysms arising from the posterior cerebral artery was treated by clipping the P2 segment of the artery, proximal to the first aneurysm. This combination of aneurysms has not previously been reported.

Cerebral Angiography↗
PubMed1990

Spinal surgery.

Explore the source record for details and available documents.

Chymopapain↗
PubMed1990

Cerebral radiation necrosis complicating stereotactic radiosurgery for arteriovenous malformation.

A patient presented with symptoms and signs of raised intracranial pressure and increasing focal deficit 13 months after stereotactic radiosurgical treatment of an arteriovenous malformation (AVM). Computed Tomography (CT) showed a mass lesion at the site of the previous abnormality typical of radiation necrosis, but with features identical to those of a malignant neoplasm. Biopsy confirmed cerebral radiation necrosis. The radiation dose was 25 Gray to the periphery of two overlapping 14 mm collimator fields, delivered in a single dose. Treatment with steroids led to improvement in the symptoms and signs of raised intracranial pressure, but not the focal deficit. Radiation necrosis is a consequence of the large doses required to obliterate AVMs and is a limiting factor in their treatment. It is important for clinicians referring patients for stereotactic radiosurgery to be aware of this complication, and to be able to recognise and treat it.

Adult↗
PubMed1988

Dissolution of gallstones using methyl tertiary-butyl ether in an animal model.

Human gallstones were surgically implanted in the gallbladders of six pigs. Through cholecystostomy catheters, methyl tertiary-butyl ether (MTBE) was infused from 3 to 5 days. MTBE successfully dissolved 19 of the 20 cholesterol stones and partially dissolved one mixed cholesterol-bilirubin stone. Gross and microscopic examination of abdominal organs revealed mild superficial ulcerations of the gallbladder and mild to moderate chronic inflammatory changes in the gallbladder of animals treated with MTBE infusion. There were no other significant changes within other abdominal organs except for mild inflammation of the duodenum in one animal and of the common bile duct in another. Because of its efficacy and limited deleterious effects, MTBE may be a good solvent when dissolving pure cholesterol gallstones in the gallbladder.

Animals↗
PubMed1988

Single- and double-stranded viral RNAs in plants infected with the potexviruses papaya mosaic virus and foxtail mosaic virus.

Three classes of viral RNA were recovered from polyribosomes purified from papaya leaves infected with papaya mosaic virus (PapMV) and from barley leaves infected with foxtail mosaic virus (FoMV): full-length viral RNAs [6.8 and 6.2 kilobases (kb), respectively]; less abundant intermediate subgenomic RNAs (2.2 and 1.9 kb), and abundant, small subgenomic RNAs (1 and 0.9 kb). Small amounts of the PapMV-specified 1.0-kb subgenomic RNA were encapsidated, whereas no encapsidated subgenomic RNAs could be found in preparations of FoMV. Immunoprecipitation of the products of in vitro translation of the small subgenomic RNA of both viruses showed that it codes for the corresponding viral coat protein. FoMV genomic RNA isolated from polyribosomes also directed the efficient synthesis of a 37- to 38-kilodalton protein which was immunoprecipitated by an antiserum raised against the coat protein. We presume this product to be a readthrough protein initiated to the 5' side of and in the same reading frame as the coat protein-coding sequences in FoMV RNA. The predominant double-stranded viral-specified RNAs in tissues infected with PapMV, FoMV, and clover yellow mosaic virus were genome sized (6.8, 6.2, and 7.0 kb pairs, respectively). If double-stranded RNAs corresponding to coat protein subgenomic RNAs exist, they must be present in much lower relative abundances.

Genes, Viral↗
PubMed1987

A double-blind comparison of lisinopril with captopril in patients with symptomatic congestive heart failure.

Angiotensin-converting enzyme (ACE) inhibition with captopril is accepted therapy for the treatment of symptomatic congestive heart failure. In this trial, we compared the new ACE inhibitor, lisinopril, to captopril during a 12-week randomized double-blind study. One hundred twenty-nine patients with New York Heart Association class II, III, or IV congestive heart failure were randomized to receive either lisinopril 5 mg/day (n = 64) or captopril 37.5 mg/day (n = 65) in 15 centers. Drug doses could be titrated upwards every 4 weeks. The primary measure of drug efficacy was improvement in treadmill exercise time using a modified Naughton protocol. Secondary measures of efficacy and the development of adverse effects were also examined. Lisinopril improved exercise time (following 12 weeks of therapy) more than captopril [from 500 +/- 30 to 682 +/- 34 sec (mean +/- SEM) with lisinopril versus 480 +/- 26 to 600 +/- 35 sec with captopril; difference between groups, p less than 0.05]. Adverse drug effects were unusual and similar in frequency in the two groups, although an increase in blood urea nitrogen was more common with lisinopril than with captopril (p less than 0.05). These results indicate that using the doses and treatment regimens studied, lisinopril is more effective than captopril for the treatment of symptomatic congestive heart failure. Adverse experiences with lisinopril were infrequent and similar in incidence to those observed with captopril.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1987

MRI measurement of syrinx size before and after operation.

When patients with syringomyelia fail to improve after operation, factors such as incomplete cyst decompression or type of operation are often implicated. MRI has been used to confirm adequate syrinx decompression post-operatively and to compare the degree of collapse with the type of operation. Foramen magnum decompression was at least as effective in reducing cyst size as syringo-subarachnoid shunting. MRI may also provide a better classification of syringomyelia.

Foramen Magnum↗
PubMed1986

Neuroleptic bioavailability, psychosocial factors, and clinical status: a 1-year study of schizophrenic outpatients after dose reduction.

Serum neuroleptic levels, prolactin levels, and clinical state were assessed for 1 year in 29 schizophrenic outpatients whose clinically determined neuroleptic dose had been reduced by 50%. Fifty-five percent of the subjects remained stable. Neuroleptic dose did not differ between relapsed and stable patients. Serum prolactin (PRL) assessed 2 weeks after dose reduction and mean PRL after reduction were significantly lower among relapsers. Serum neuroleptic levels were significantly lower for relapsers in patients on haloperidol. Among relapsers, there were no serum PRL or neuroleptic level differences between stable periods and the relapse episode. Among patients with relatively low neuroleptic bioavailability, relapsers reported lower levels of social activity and had social networks that were less enjoyable, more aversive, and less helpful than those of stable patients.

Adult↗