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Biomedical subjects

M B Johnson

Publications and source records attributed to M B Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1990

Assessment of the lymphocyte response to silicone.

The biocompatibility of silicone is once again the focus of increased interest. Long considered inert, silicone has now been reported to be responsible for macrophage inhibition in rats and to possibly cause adjuvant disease in humans, and the related compound silica has elicited an antibody response in mice. The present study evaluates lymphocytic response to silicone as expressed by the demonstration of immunologic memory, or changes in specific lymphocyte subpopulations. Thirty-six female Lewis rats (250 gm body weight) were used as test animals. Group 1 (n = 12) was injected subcutaneously with 2.5 ml Freund's Complete Adjuvant (FCA) alone. Group 2 (n = 12) was injected with 2.5 ml FCA sonicated with silicone gel. Group 3 (n = 6) was injected with 2.5 ml FCA, and at 4 weeks, gel-filled silicone implants were placed subcutaneously. Group 4 (n = 6) was injected with 2.5 ml FCA sonicated with silicone gel, and gel-filled silicone implants were placed at 4 weeks. An additional group of six rats (group 5) served as control for the experimental animals, and a group of four rats (group 6) served as naive control. Groups 1 and 2 were sacrificed at 4 weeks, and splenic lymphocytes were obtained for lymphocyte transformation assays performed against silicone. Assays also were run with the addition of the known mitogens Con A, PHA, LPS, and pokeweed. Cytofluorographic analysis of pan-T, T-helper, T-suppressor, and B-cell populations was performed. Groups 3, 4, 5, and 6 were harvested at 8 months, and splenic lymphocytes were subjected to lymphocyte transformation assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Pulsed Doppler sonography of the hepatoduodenal ligament: efficacy and ease of performance.

A prospective analysis of the hepatoduodenal ligament (HDL) in 205 patients with abdominal pulsed Doppler sonography supports the conclusion that Doppler ultrasound is a useful adjunct to routine scanning in this area. Abdominal pulsed Doppler sonography allows reliable differentiation among the HDL structures by identifying and characterizing flow in the portal vein and hepatic arterial structures, while demonstrating no flow in the bile ducts. Proper hepatic arterial signal was obtained in 190 (92.7%) patients. Portal venous signal was obtained in virtually all (203 of 205-99%) patients. Abdominal Doppler sonography shows promise in its ability to provide definitive diagnostic information in situations where images alone may prove misleading. Doppler sonography can differentiate similarly sized bile ducts and arteries and detect dilated arterial and venous structures simulating dilated bile ducts.

Common Bile Duct↗
PubMed1988

FM sonography in gallbladder disease: efficacy and comparison with conventional sonography.

A new type of ultrasound signal processing ("FM sonography") appears to be beneficial compared to conventional ultrasound ("AM sonography") in some applications (e.g., diffuse liver disease and prostatic carcinoma). Despite these possible advantages, it is doubtful FM sonography will be widely used unless it is at least as useful as conventional (AM) sonography in all common applications. Fifty-five patients with suspected gallbladder disease were independently evaluated with both AM and FM sonography. The two modalities were blindly and prospectively compared for accuracy in detecting gallstones and for image quality. No statistically significant difference was found between images produced by FM and conventional signal processing. FM had an accuracy of detecting gallstones of 98.1%, compared to 96.2% for AM. Overall, FM accuracy was 97.7%, while AM had an overall accuracy of 97.3%. Other useful sonographic signs were evaluated (gallbladder wall thickness, diameter of common duct). No AM/FM difference was noted. Our data suggest that FM-only imaging could be performed in patients with suspected gallbladder disease without loss of accuracy.

Cholelithiasis↗
PubMed1988

The significance of clinical change and clinical change of significance: issues and methods.

The emphasis on systematic methods of demonstrating accountability in health care is affecting the delivery of human services at all levels, from hospitals and community centers to individual private practitioners. New procedures are being proposed to meet the accountability demands encountered by therapists. Several recently developed methods for documenting clinical change in patient status are presented, and the relationship of this documentation to traditional research methods is briefly explored. A clinical illustration of the procedures is provided along with a discussion of advantages and limitations.

Child↗
PubMed1988

Galveston Orientation and Amnesia Test: its utility in the determination of closed head injury in acute spinal cord injury patients.

The incidence of closed head injury (CHI) associated with acute spinal cord injury (SCI) has been estimated at 40% to 50%. Closed head injury can be defined as the presence of loss of consciousness (LOC) and/or posttraumatic amnesia (PTA). Consequently, one of the difficulties in establishing a diagnosis of CHI is determining the existence of PTA in those patients without documented LOC. Previous work described the inconsistent evaluation of PTA in the SCI population. This study was conducted to evaluate the utility of the Galveston Orientation and Amnesia Test (GOAT) in establishing the diagnosis of CHI in a series of acute traumatic SCI patients. The GOAT was administered serially for three to five days to 34 patients admitted to our hospital. When information derived from the GOAT was added to that derived from review of medical records alone, the observed incidence of PTA (and by implication CHI) increased significantly (McNemar statistic = 6.4; p = 0.01). The GOAT is a quick, simple, and reproducible evaluation of spheres of orientation, which is extremely helpful in diagnosis of PTA in this population. This instrument should be used to evaluate patients at high risk for head injury. Although abnormalities in the GOAT evaluation may also be attributable to factors other than CHI (eg, hypoxia, medication effects), such findings provide evidence suggestive of CHI. This will help determine which patients require a more detailed neuropsychologic assessment.

Adult↗
PubMed1987

Cholelithiasis: evaluation with CT.

Computed tomography (CT) is often the first imaging modality used in the diagnosis of patients with suspected abdominal disease. While it is known that early generation CT scanners often detect gallstones, the detection rate of newer equipment is not widely known. Abdominal CT scans of 226 patients who had undergone ultrasonographic (US) studies of the gallbladder were reviewed in a blinded study to determine the accuracy of state-of-the-art CT scanning equipment in the detection of cholelithiasis. Of 110 patients with US or surgical evidence of cholelithiasis, gallstones were demonstrated on CT images of 87 (79.1% sensitivity). Overall accuracy was 89.8%, while specificity was 100%. On CT images stones could appear densely (48.3%) or slightly (11.5%) calcified, as an area with a rim of increased density (21.8%), as an area of soft-tissue density (14.9%), or as an area of low density (3.4%). Stone size, stone density, section incrementation, and the pericholecystic anatomy affected the detection rate. Understanding the spectrum of findings and the other factors involved can optimize success of diagnosis of cholelithiasis on the basis of CT examinations.

Cholecystography↗
PubMed1987

Medical treatment of hepatic amebic abscess: rare need for percutaneous drainage.

Although amebic liver abscess can virtually always be successfully treated medically, percutaneous drainage has been advocated recently. In 96 recently treated patients, therapeutic aspiration and percutaneous drainage were rarely needed. Most cases were correctly diagnosed by means of clinical, laboratory, and sonographic findings. Abscesses in only 13 (13.5%) patients were diagnostically aspirated. An abscess in one patient was therapeutically aspirated because the patient was responding slowly to medical therapy. No patient required catheter drainage. The key to successful amebic abscess management is medical therapy. Therapeutic drainage is rarely needed. Successfully treated patients occasionally respond slowly to medical therapy, and successfully treated amebic abscesses may enlarge or become bizarre-appearing on sonograms. This should not prompt therapeutic drainage. Diagnostic aspiration is appropriate when amebic and pyogenic abscesses are indistinguishable using clinical and imaging findings. Rare indications for therapeutic aspiration or drainage include pyogenic superinfection and large, juxtacardiac abscesses (potential intrapericardial rupture).

Chloroquine↗
PubMed1986

Quantitative analysis of the effectiveness of pediatric therapy. Emphasis on the neurodevelopmental treatment approach.

We investigated the effectiveness of neurodevelopmental treatment when used both in isolation and in combination with other developmental therapies. The data were analyzed using recently developed methods of quantitatively synthesizing research results in which the literature review process is regarded as a unique type of research. Our analysis revealed that the subjects who received NDT performed slightly better than the control-comparison subjects who did not receive the intervention. The study outcomes are discussed in relation to several design variables and study characteristics associated with subject performance. The advantages and limitations of quantitative reviewing are identified briefly, and the potential use of the procedures in clinical research is emphasized.

Cerebral Palsy↗
PubMed1986

FM sonography in diffuse liver disease: prospective assessment and blinded analysis.

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.

Hepatitis↗
PubMed1985

Is there a limit on in situ, genomic replication in Drosophila?

The number of genomic replications of four separate tissues was determined in Drosophila melanogaster by summing the total number of nuclei and the maximum amount of DNA per nucleus in each tissue. It was found that for a given tissue the total number of nuclei was generally inversely proportional to the maximum amount of DNA per nucleus. In addition the sum of the number of divisions giving rise to the nuclei and the number of DNA replications occurring in the nucleus in each tissue never exceeded 20.

Aging↗
PubMed1985

Maturation and aging of adult fat body and oenocytes in Drosophila as revealed by light microscopic morphometry.

A morphological and cytometric analysis of the adult fat body cells and oenocytes was made on sections of abdomens from immature, mature and senescent Drosophila melanogaster of both sexes. There are about 18,000 fat body cells in abdomens of female and mature male flies. Immature and senescent males have about 12,000 and 15,000 cells, respectively. The size of the cells is almost the same for immature flies of both sexes and increases about six-fold to approximately 2600 micron2, so that mature flies of both sexes have equivalent amounts of fat body tissue. The proportions of lipid, glycogen, and background cytoplasm of fat body cells also remain relatively constant throughout adult life, but dense, proteinaceous granules are observed in cells of senescent flies. The amounts of cellular components change dramatically due to change of cell size with age; the amount of lipid shows the greatest sexual difference with about 2x more in the females at all stages studied. The oenocytes number about 6,000 in the abdomens of all but immature male flies, which have approximately 4,000. Although the cells of both sexes triple in size to about 700 micron 2, the oenocytes of males reach maximum size earlier than those of females. The major features of oenocytes appear to be dense background cytoplasm, putative lipid droplets found only in mature flies, and pigmented granules first seen in the cells of mature flies which accumulate with age to 33% of the cytoplasm. The number of cells and their anticipated capacity for protein synthesis is discussed in relation to the production of yolk protein precursors.

Adipose Tissue↗
PubMed1983

Radical irradiation and misonidazole in the treatment of T2 grade III and T3 bladder cancer.

The results of 2 pilot studies using a new radiation fractionation schedule plus misonidazole (MISO) in the radical radiotherapy of T2 Grade III and T3 carcinoma of the bladder are presented. Forty Gy in 20 daily fractions of 2 Gy was administered to the whole pelvis over 4 weeks followed by 12 Gy in 2 weekly fractions of 6 Gy. These last 2 doses were given after MISO administration. In an initial pilot study (Pilot Study I) MISO was administered orally only. The first two patients received MISO at a dose of 4.5g/m2 orally with each radiation fraction, after which the dose was reduced to 3.0g/m2 because of drug toxicity. In the second pilot study (Pilot Study II) MISO was administered orally at a dose of 3.0g/m2 and intravesically at a dose of 1.0g to 22 patients. The complete response rate at cystoscopy at 6 months in the latter group of patients is 73%, which is significantly better than that of 43% obtained in a retrospective study of historical controls. There have been no late radiation complications in any of the patients nor any MISO toxicity apart from nausea in the patients receiving 3.0g/m2 orally with or without the intravesical MISO.

Administration, Oral↗