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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 343 records · Page 19Linked to original sources
PubMed1990

Postcoital antimicrobial prophylaxis for recurrent urinary tract infection. A randomized, double-blind, placebo-controlled trial.

We conducted a randomized, double-blind, placebo-controlled study to determine the efficacy of postcoital antibiotic prophylaxis in healthy young women prone to recurrent urinary tract infections. Sixteen patients were randomized to receive postcoital administration of a combination product of trimethoprim and sulfamethoxazole, while 11 received postcoital placebo. The treatment groups were similar with respect to age, parity, diaphragm use, history of lifetime urinary tract infections, frequency of intercourse, and number of lifetime sexual partners. In over 6 months of observation, postcoital administration of trimethoprim-sulfamethoxazole was highly effective in preventing recurrent urinary tract infections. Nine of 11 patients who took the placebo developed urinary tract infections (infection rate, 3.6 per patient-year), compared with only two of 16 patients who received postcoital trimethoprim-sulfamethoxazole (infection rate, 0.3 per patient-year). Postcoital administration of trimethoprim-sulfamethoxazole was effective in patients with both low (two or fewer times per week) and high (three or more times per week) intercourse frequencies. Side effects were few and compliance was excellent. We conclude that postcoital trimethoprim-sulfamethoxazole is a safe, effective, and inexpensive approach to management of recurrent urinary tract infections in young women.

Adult↗
PubMed1990

Frequent deletions of the human X chromosome distal short arm result from recombination between low copy repetitive elements.

Substantial DNA deletions appear to be the molecular basis of several human genetic disorders but rarely account for the majority of observed mutations at any given locus. Exceptions in which deletions do account for the majority of observed abnormalities include the alpha-thalassemias, Duchenne muscular dystrophy, and steroid sulfatase deficiency. Variable deletion breakpoints have been recognized at the alpha-globin and dystrophin loci, but no information is available regarding STS deletions. We have found that these STS alterations usually involve breakpoints within highly similar sequence elements situated approximately 1.9 megabases apart on the X chromosome. It is surprising that these very large deletions produce such mild clinical abnormalities. These results may provide insight into the molecular mechanism of a number of human genetic defects.

Cell Line↗
PubMed1990

The cyanelle genome of Cyanophora paradoxa, unlike the chloroplast genome, codes for the ribosomal L3 protein.

We describe a 1132 bp sequence of the cyanelle genome of Cyanophora paradoxa containing the rpl3 gene. This gene, which is not chloroplast encoded in plants, is the first of a long cyanelle ribosomal operon whose organization resembles that of the S10 operon of E. coli. We have shown that the rpl3 gene is transcribed in cyanelles as a 7500 nucleotide precursor and that the 5'-end of the mRNA starts approximately 90 nucleotides upstream from the initiation codon. However, no typical procaryotic promoter could be found for this gene. We have detected, using anti E. coli L3 antibodies, the cyanelle L3 protein in cyanelle extracts and in E. coli cells transformed with the cyanelle rpl3 gene.

Amino Acid Sequence↗
PubMed1990

Stage D1 prostate carcinoma. The histologic appearance of nodal metastases and its relationship to survival.

Eighty-two of 307 consecutive staging lymphadenectomies had nodal metastases (Stage D1 prostate carcinoma). Seventy-seven of the 82 cases had at least a 5-year follow-up and 50 had at least a 10-year follow-up. Three of these 77 cases had Grade 1 (well-differentiated) metastases, 59 (77%) had Grade 2-3 (moderately differentiated) metastases, and 15 (19%) had Grade 4 (poorly differentiated) metastases (M. D. Anderson Hospital [MDAH] grading system). The patients with moderately differentiated metastases had 5-year and 10-year survival rates of 79% and 34%, respectively, whereas the patients with poorly differentiated metastases had 5-year and 10-year survival rates of 13% and 0%, respectively (P less than 0.0001). This study demonstrates a statistically significant difference between the prognosis of Stage D1 patients with moderately differentiated metastases and Stage D1 patients with poorly differentiated metastases. Consequently, the evaluation of the histologic appearance of Stage D1 metastases may be of clinical importance.

Carcinoma↗
PubMed1990

Osteochondritis dissecans of the knee: arthroscopic compression screw fixation.

This article describes repair of osteochondritis dissecans of the knee by arthroscopic compression screw fixation and reports the healing response and clinical result. Diagnostic and operative arthroscopy was performed. Compression screw fixation was used. The exact operative technique varied depending on the status of the lesion. The patients were non-weight bearing for 2 months, after which a second surgery was necessary for removal of the metallic screw(s). The initial healing response was assessed by the firmness of the lesion to palpation at the second look. Subsequent x-ray evidence of healing was correlated with the clinical outcome. Ninety-four percent of the knees were determined to be initially healed at the time of the second look. Four of these apparently solid repairs subsequently loosened and required repeat surgery. Eighty-eight percent of the patients assessed their results as excellent or good after 2 years minimum follow-up. Arthroscopic compression screw fixation is an effective method of repair for mild to moderately severe cases of osteochondritis dissecans.

Adult↗
PubMed1990

Primary bone grafting following graft procurement for anterior cruciate ligament insufficiency.

A technical recommendation of primarily bone grafting the patellar tendon graft site created following harvesting the central third of the free bone-tendon-bone patellar tendon graft for anterior cruciate ligament (ACL) insufficiency is presented. Harvesting a patellar bone-tendon-bone graft produces a stress riser that increases the potential risk of a patellar fracture. Primary bone grafting of the patellar region is recommended as a simple and safe solution, especially if a graft wider than 10-12 mm or deeper than 6 mm is taken. We feel that this will reduce even further the small likelihood of late patellar fracture. Using these principles, we have not had any late patellar fractures in over 135 consecutive ACL reconstructions since July, 1986.

Anterior Cruciate Ligament↗
PubMed1990

Combined mechanical and chemical thrombolysis in an experimental animal model: evaluation by angiography and angioscopy.

In an experimental animal model of femoral artery thrombosis, contrast angiography was compared to intravascular angioscopy. Additionally, the effect of mechanical, rotational thrombectomy and the additive benefit of the administration of intravascular streptokinase were assessed by means of both procedures. After external forceps crush injury alone, contrast angiograms were generally normal (6 of 14) or showed minimal luminal irregularity (3 of 14), and 5 of 14 had 30% to 50% stenosis. With angioscopy, none appeared normal, and 14 of 14 showed thrombi layered along the wall, as well as intimal flaps, and 6 of 14 had partially occlusive thrombi (p less than 0.001 angiography vs angioscopy). After 2-hour occlusion and injection of thrombin into the injured segment, angiographic total (5 of 14), subtotal (3 of 14), or partial thrombotic occlusions (5 of 14) were created. Angioscopy showed similar results, except that total occlusions were classed as subtotal occlusions. After rotational thrombectomy, most arteries again appeared normal by contrast angiography (6 of 11) but none were angioscopically normal (p less than 0.006). Streptokinase, administered after rotational thrombectomy in seven arteries, normalized one 30% angiographic stenosis; there were no other angiographic changes. Findings with angioscopy were also unchanged. We conclude that in the diagnosis and treatment of intravascular thrombosis, angioscopy is generally more sensitive in the detection of intravascular thrombi, with the exception of total thrombotic occlusions. Angioscopy was uniquely effective in identifying subintimal flaps, which were never identified by angiography. In this model, streptokinase provided little or no additional thrombolytic benefit to mechanical thrombectomy alone.

Angiography↗
PubMed1990

Molecular cloning and chromosome mapping of the human gene encoding protein phosphotyrosyl phosphatase 1B.

The inactivation of growth suppressor genes appears to play a major role in the malignant process. To assess whether protein phosphotyrosyl phosphatases (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) function as growth suppressors, we have isolated a cDNA clone encoding human protein phosphotyrosyl phosphatase 1B for structural and functional characterization. The translation product deduced from the 1305-nucleotide open reading frame predicts a protein containing 435 amino acids and having a molecular mass of 49,966 Da. The amino-terminal 321 amino acids deduced from the cDNA sequence are identical to the empirically determined sequence of protein phosphotyrosyl phosphatase 1B. [Charbonneau, H., Tonks, N. K., Kumar, S., Diltz, C. D., Harrylock, M., Cool, D. E., Krebs, E. G., Fischer, E. H. & Walsh, K. A. (1989) Proc. Natl. Acad. Sci. USA 86, 5252-5256]. A genomic clone has been isolated and used in an in situ hybridization to banded metaphase chromosomes to determine that the gene encoding protein phosphotyrosyl phosphatase 1B maps as a single-copy gene to the long arm of chromosome 20 in the region q13.1-q13.2.

Amino Acid Sequence↗
PubMed1990

Interaction of epsilon-globin cis-acting control elements with erythroid-specific regulatory macromolecules.

We have used a competition assay to investigate the influence of erythroid-specific cellular factors on transcription from the human epsilon-globin major cap site promoter and the minor promoter located 200 base pairs (bp) upstream from the epsilon-globin cap site. In the human erythroid cell line K562, competition of the epsilon-globin major cap site promoter linked to the chloramphenicol acetyltransferase (CAT) gene (epsilon P-CAT) with the same promoter fragment linked to a neomycin resistance gene (epsilon P-NEO) leads to a reduction in CAT activity. This indicates the specific presence of K562 cells of factor(s) which interact with the 200-bp promoter fragment (isolated from the gene body or flanking sequences) to activate transcription from the epsilon-globin major cap site. Competition of the epsilon-globin major promoter (as epsilon P-CAT) with the upstream minor epsilon-globin promoter (as epsilon P2-NEO) also leads to a reduction in CAT activity, indicating that both promoters share erythroid-specific trans-acting factors. The reverse competition (epsilon P2-CAT with epsilon P-NEO) leads to an increase in CAT activity, suggesting that the existence of erythroid-specific factor(s) which repress transcription from the 200-bp-upstream epsilon-globin promoter.

Cell Line↗
PubMed1990

Structural and functional effects of long-term alcohol administration on the dog exocrine pancreas submitted to two different diets.

Our purpose was to study the influence of two different levels of dietary protein and fat on the action of chronic alcohol feeding on the exocrine pancreatic secretion and the pancreatic morphology of conscious dogs. Ten animals were provided with gastric and duodenal cannulas. Five of them (group H) received a high-protein (39% of calories), high-fat (34%) diet, and the five others (group L) a moderately low-protein (15%), low-fat (20%) diet. Animals were housed in closed kennels lightened with artificial light and did not have free access to sunlight. Five series of experiments were performed just before and 5 and 12 months after daily alcohol administration through the gastric cannula (2 g/kg/day). Volume, bicarbonate, and protein were measured under basal conditions after intragastric ethanol infusion (1.5 g/kg), under hormonal stimulation with 1 clinical unit (CU)/kg/h secretin or 1 CU/kg/h secretin plus 3 Crick Harper Rate (CHR) U/kg/h cholecystokinin (CCK), before and after intravenous ethanol 1.3 g/kg for 20 min, and after intragastric ethanol (1 g/kg) given with a meal. Group H was the most sensitive to the action of chronic alcohol feeding. At the end of 1 year of alcohol administration, volume and bicarbonate were not affected, but protein secretion was significantly increased in basal conditions and under secretin infusion, but not under CCK infusion or in response to a meal. The secretory pattern of these dogs was different from the response of dogs studied in previous experiments having the same diet but housed in an open kennel and having free access to outside and sunlight. In group L, protein was less affected, but volume and bicarbonate were significantly decreased 1 year under secretin stimulation. Histological damages were seen in the two groups characterized by a slight periacinar fibrosis and alterations of ductal cells. Acinar and ductal luminae were dilated and filled with protein plugs also present in pancreatic juice and able to stop the flow of juice. At the difference from human beings, these plugs were built up of all secretory protein but not of an insoluble fibrillar molecular form of pancreatic stone protein. This study confirms the role of chronic alcoholism on the formation of protein plugs and shows the influence of nutritional and environmental conditions.

Alcoholism↗
PubMed1990

Comparison of cefuroxime axetil, cefaclor, and amoxicillin-clavulanate potassium suspensions in acute otitis media in infants and children.

In this randomized, blinded, multicenter comparison study, 377 infants and children with acute otitis media (AOM) received a 10-day course of an oral suspension of one of the following: cefuroxime axetil (CAE), 30 mg/kg/day; cefaclor (CEC), 40 mg/kg/day; or amoxicillin-clavulanate potassium (AMX-CL), 40 mg/kg/day. Clinical efficacy was determined by pneumatic otoscopy and tympanometric testing 3 to 5, 11 to 14, and 22 to 26 days after the initiation of therapy. There was a statistically significant difference among the three treatment groups with respect to clinical outcome; more patients in the CAE group (62%) than in the CEC group (46%) or the AMX-CL group (52%) had complete resolution of signs and symptoms of AOM (including effusion). Paired comparisons revealed a significant difference in efficacy between CAE and CEC and a nearly significant difference between AMX-CL and CEC. Taste acceptability was highest for CEC and lowest for this formulation of CAE. Significantly more patients in the AMX-CL group than in the CAE or CEC group had a side effect, primarily diarrhea, vomiting, or diaper rash. We conclude that CAE suspension has greater clinical efficacy than CEC and fewer side effects than AMX-CL.

Acoustic Impedance Tests↗
PubMed1990

Specialisation in general surgery.

This survey was designed to determine the current status of specialisation within general surgery amongst newly appointed consultants in the United Kingdom, and to document the extent of specialist training on programmes of higher surgical training. It was carried out in 1988 under the auspices of the Association of Surgeons in Training, to determine whether consultants appointed in recent years had maintained, developed, or abandoned subspecialist practice. A separate survey of senior registrars in general surgery examined their attitudes to the apparent need to offer a special interest at the time of consultant appointment, and afterwards in practice. Although a majority of general surgical trainees and newly appointed consultants support specialist training as a part of higher surgical training programmes, this survey suggests that some programmes are not achieving this ideal.

Attitude of Health Personnel↗
PubMed1990

Serum lipids and lipoproteins of Hispanics, 1982-84.

This report presents descriptive data for serum lipids and lipoproteins by age, sex, and selected socioeconomic variables. This information is from the Hispanic Health and Nutrition Examination Survey, a sample survey of selected groups of civilian noninstitutionalized Hispanic persons residing in selected area of the United States, that was conducted during the period 1982-84.

Adult↗