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Biomedical subjects

H J Smith

Publications and source records attributed to H J Smith.

At least 19 recordsLinked to original sources
PubMed1992

Imaging temporomandibular joint abnormalities in patients with rheumatic disease. Comparison with surgical observations.

The preoperative examination findings in the soft tissue and bone of 22 temporomandibular joints of 15 patients with rheumatic disease were compared with the diagnosis after TMJ surgery. Agreement was found in 15 joints with rheumatic involvement and in 4 with internal derangement. In 5 (with unsuccessful arthrotomography) of the 15 rheumatic joints, magnetic resonance imaging showed destruction of disks with soft-tissue replacement, corresponding to fibrous tissue/ankylosis observed at surgery. Bony fusions in 2 of these joints were depicted with computed tomography. In the remaining 10 joints, arthrotomography showed irregularly outlined small compartments corresponding to synovial proliferations observed during surgery. Similar arthrotomographic interpretation, however, was made in 2 of 3 temporomandibular joints with imaging-surgery disagreement; surgery showed fibrous adhesions. In the third joint with unsuccessful arthrotomography, magnetic resonance imaging showed internal derangement but no synovial proliferations that were surgically observed. As experienced with other joints, synovial proliferations (or fibrous adhesions) could not be depicted with magnetic resonance imaging. Thus, differentiation between internal derangement with and without rheumatic involvement could be impossible with both arthrotomography and unenhanced magnetic resonance imaging.

Adolescent↗
PubMed1992

Temporomandibular joint abnormalities associated with rheumatic disease: comparison between MR imaging and arthrotomography.

Nonenhanced magnetic resonance (MR) images and arthrotomograms of temporomandibular joints (TMJs) were compared in 18 patients with rheumatic disease. Of 22 symptomatic TMJs, arthrotomography was unsuccessful in three (14%). MR imaging showed extensive rheumatic abnormalities in two of these three joints and internal derangement in one. In another three joints (14%), both imaging modalities showed normal findings or internal derangement. In the remaining 16 joints (72%), arthrotomographic findings were interpreted as rheumatic, whereas MR findings were interpreted as rheumatic in 14 joints and as internal derangement in two. Surgical correlation in 11 joints indicated superiority of MR imaging for assessment of moderate and severe rheumatic TMJ involvement. MR imaging seemed to be of limited value in early diagnosis due to its inability to show synovial proliferation. Indirect signs of synovial proliferation could be shown with arthrotomography, which may be helpful in early diagnosis of rheumatic TMJ disease.

Adolescent↗
PubMed1992

Rheumatic and nonrheumatic disease in the temporomandibular joint: gadolinium-enhanced MR imaging.

Magnetic resonance (MR) imaging of 36 temporomandibular joints (TMJs) in 27 patients and six healthy volunteers was performed before and after injection of gadopentetate dimeglumine. Twelve asymptomatic joints were used as controls, 12 TMJs had symptomatic internal derangement, and 12 TMJs had rheumatic inflammatory disease. A small or moderate joint effusion was seen in one asymptomatic joint, four joints with internal derangement, and one joint with rheumatic involvement; in all of these, contrast enhancement of the effusion was observed. A large effusion in one rheumatic joint was enhanced only after delayed imaging. In healthy controls and patients with internal derangement, no or only minimal enhancement of intraarticular tissues was seen. Eleven of the 12 rheumatic TMJs showed moderate or intense soft-tissue enhancement along the disk and articular surfaces (ie, in areas normally devoid of synovial membrane). The one rheumatic joint without enhancement had bony ankylosis and no remaining soft tissue within the joint space. Gadolinium-enhanced MR imaging of the TMJ may effectively depict the proliferating synovium of rheumatic inflammatory joint disease.

Adolescent↗
PubMed1992

Novel inhibitors of enkephalin-degrading enzymes. IV: Structure-activity relationships within the penicillins as enkephalinase inhibitors.

A range of penicillins have been examined as competitive reversible inhibitors of enkephalinase (neutral endopeptidase; EC 3.4.24.11). Carfecillin (Ki = 0.18 microM) was the most potent inhibitor in the series, whereas cloxacillin (27.5 microM), ampicillin (41.0 microM), nafcillin (58.7 microM) and carbenicillin (158 microM) had moderate potency and benzyl penicillin (885 microM), mezlocillin (473 microM) and azlocillin (556 microM) were weak inhibitors. Structure-activity relationships within the series have been rationalised from a consideration of molecular graphics analysis of the match between receptor binding groups with thiorphan as well as log P values.

Computer Graphics↗
PubMed1992

Some 1-, and 3-substituted 3-(4'-aminophenyl)pyrrolidine-2,5-diones as selective inhibitors of aromatase.

1-Alkyl-3-(4'aminophenyl)pyrrolidine-2,5-diones (7,R = C3H7-C7H15) are potent inhibitors of aromatase in vitro, the 1-hexyl (Ki = 62nM) being about 100-fold more potent than aminoglutethimide (AG), and more selective in their ratio of aromatase:CSCC inhibitory potency. The 1-pentyl, 1-hexyl and 1-heptyl derivatives are more stable to liver microsomal metabolism in vitro than AG possibly due to inhibition of the liver cytochrome P450s. 1,3-Dialkyl-3(4'-aminophenyl)pyrrolidine-2,5-diones (9) have been synthesised by a novel method. Although the higher homologues (di-pentyl and di-hexyl) are more potent in vitro as inhibitors of aromatase than AG, they are less active than their 1-alkyl counterparts with the same alkyl substituent.

Adrenal Glands↗
PubMed1992

Comparison of 12-bit and 8-bit gray scale resolution in MR imaging of the CNS. An ROC analysis.

A reduction in gray scale resolution of digital images from 12 to 8 bits per pixel usually means halving the storage space needed for the images. Theoretically, important diagnostic information may be lost in the process. We compared the sensitivity and specificity achieved by 4 radiologists in reading laser-printed films of original 12-bit MR images and cathode ray tube displays of the same images which had been compressed to 8 bits per pixel using a specially developed computer program. Receiver operating characteristic (ROC) curves showed no significant differences between film reading and screen reading. A paired 2-tailed t-test, applied on the data for actually positive cases, showed that the combined, average performance of the reviewers was significantly better at screen reading than at film reading. No such differences were found for actually negative cases. Some individual differences were found, but it is concluded that gray scale resolution of MR images may be reduced from 12 to 8 bits per pixel without any significant reduction in diagnostic information.

Central Nervous System↗
PubMed1991

[Magnetic resonance angiography--the start of the end of conventional angiography?].

Magnetic resonance angiography (MRA) is a new, non-invasive technique using magnetic resonance imaging to create projection images of vessels. The article gives a simplified explanation of the basic principles involved, and presents the preliminary experiences at Rikshospitalet, the National Hospital of Norway, using magnetic resonance angiography in the study of carotid and renal arteries. It is concluded that this method holds promise for more extensive use in the future. The method is likely to replace at least some of the routine conventional angiography performed today.

Angiography↗
PubMed1991

Rheumatic disease of temporomandibular joint with development of anterior disk displacement as revealed by magnetic resonance imaging. A case report.

A 34-year-old woman with known rheumatic disease (psoriatic arthritis) in joints other than the temporomandibular joint (TMJ) developed condylar posterosuperior destruction and anterior disk displacement of the right symptomatic TMJ during a 7-month period, as revealed by magnetic resonance imaging. A theory is proposed that destruction of the posterior attachment by pannus was the main reason for the disk displacement, although the pannus formation itself could not be depicted. Follow-up studies also indicated the potential of magnetic resonance imaging to demonstrate fluctuation of inflammatory changes in the TMJ.

Adult↗
PubMed1991

Novel inhibitors of enkephalin-degrading enzymes. III: 4-Carboxymethylamino-4-oxo-3 (phenylamino) butanoic acids as enkephalinase inhibitors.

4-Carboxymethylamino-4-oxo-3-(4'-aminophenylamino) butanoic acid (25), its ethyl ester (26) and the corresponding unsubstituted-aryl analogues (17) and (16) are fairly potent inhibitors of enkephalinase (neutral endopeptidase; EC 3.4.24.11), Ki = 0.14-0.39 microM, with weak inhibitory potency, Ki = 15-75 microM, towards aminopeptidase MII. In the mouse abdominal constriction test, the esters (26) and (16) showed systemic inhibitory (antinociceptive) activity with ED50 values 62 +/- 3.05 and 81 +/- 1.74 mg/kg respectively. In the mouse tail immersion test, both (26) and (16) exhibited antinociceptive activity when administered intracerebroventricularly and (26) also exhibited a systemic effect which was only partially reversed by naltrexone. The antinociceptive effect seen with (26) reflects its ranking in vitro as an inhibitor of enkephalinase (Ki = 0.14 microM) but it is possible that this effect is not totally opioid-mediated. Compounds (26) and (16) represent the first combined inhibitors of enkephalinase and aminopeptidase MII.

Abdomen↗
PubMed1991

Seroprevalence of anti-Toxoplasma IgG in Canadian swine.

In 1990, 1443 sera randomly selected by computer generated random numbers from a bank of greater than 15,000 sera collected earlier from sows at slaughter in various geographic regions of Canada were tested for anti-Toxoplasma immunoglobin G (IgG) by the modified direct agglutination test. One hundred and thirty-six (9.4%) samples were positive for anti-Toxoplasma IgG while 36 (2.5%) of the sera gave borderline reactions. The highest prevalence of anti-Toxoplasma IgG was in swine originating in the Atlantic provinces and Ontario while the lowest was in swine from Manitoba and Saskatchewan.

Animals↗
PubMed1991

Immunity in swine inoculated with larvae or extracts of a pig isolate and a sylvatic isolate of Trichinella spiralis.

Inoculation of swine with a sylvatic isolate of Trichinella spiralis, designated T s nativa, resulted in low numbers of muscle larvae, compared with muscle larvae accumulation in swine inoculated with a pig type of T s spiralis. Despite low infectivity of T s nativa for swine, primary inoculation resulted in high levels of immunity against challenge infection with T s spiralis. This immunity was expressed in accelerated expulsion of challenge adults from the intestine and reduced numbers of muscle larvae. Pigs inoculated with T s nativa developed cellular and humoral responses similar to those in pigs inoculated with T s spiralis. However, in immunoblots, sera from pigs inoculated with T s nativa recognized additional proteins in muscle larvae excretory-secretory (ES) products, compared with sera from pigs inoculated with T s spiralis. Active immunization of pigs with ES products from T s nativa resulted in numerically higher, but not significantly different levels of immunity, compared with pigs immunized with ES from T s spiralis. The highest levels of immunity were obtained in pigs immunized with a T s spiralis newborn larval extract. The combination of ES products and newborn larval extract did not result in additive levels of immunity. These results indicate that the major immune effector response to Trichinella sp in pigs is against the newborn larvae, regardless of the genetic type of Trichinella sp.

Animals↗
PubMed1991

Eosinophilic myositis in Canadian cattle.

Musculature from 198 Canadian cattle with suspected lesions of eosinophilic myositis were examined histologically and by pepsin digestion. Sera from 51 of the 198 animals were also examined by enzyme-linked immunosorbent assay (ELISA) for anti-Trichinella antibodies. Viable larvae of Trichinella were not recovered from any of the cattle but one animal from Ontario tested positive for anti-Trichinella antibodies. Histologically, focal and/or diffuse eosinophilic myositis lesions were observed in 149 (75.2%) of the animals studied. Other conditions identified were sarcocystiosis, abscesses, cysticercosis, steatosis, fibrosis, granuloma, lymphosarcoma and necrosis. Sarcocystiosis was identified in 105 of the 198 animals in both normal and affected musculature. The study indicates that trichinosis is not a primary cause of eosinophilic myositis in cattle.

Animals↗
PubMed1991

Serological diagnosis of cysticercosis by an enzyme-linked immunosorbent assay in experimentally infected cattle.

Taenia saginata infections were established in four groups of calves by administering doses of 10, 10(2), 10(3) and 10(4) infective eggs respectively by gavage. A fifth group remained as uninfected controls. Sera were collected from all calves over a period of 210 days. The sera were examined by an enzyme-linked immunosorbent assay (ELISA) with a fraction of larval Taenia hydatigena cyst fluid as antigen for the presence of anti-T. saginata IgG antibodies. At slaughter, the tongue, masseter, diaphragm and cardiac muscles and liver were examined for cysticerci. The higher dose rates of T. saginata eggs were reflected in higher numbers of cysticerci found in the calves at necropsy. There was also a correlation between higher levels of antibodies produced as measured by the ELISA and the numbers of eggs given. Sero-conversion was first detected about 25 days postinfection in heavy infections and later in the lighter infections. Maximal levels of antibody occurred between 40 and 60 days postinfection, followed by a gradual decrease in levels of antibody. A secondary increase in antibody occurred between 160 and 200 days postinfection which might have been due to release of antigen after death of the cysticerci. The low level of circulating antibodies in light infections may result in false positive or false negative diagnoses depending upon the selection of the cut-off point.

Animals↗
PubMed1990

[Magnetic tomography in congenital heart defects].

Magnetic resonance imaging (MR) has been shown to be valuable in defining cardiac anatomy in a variety of cardiac abnormalities. The article describes the technique and results of MR in 32 children with congenital heart disease. MR clearly depicts the anatomy of the great vessels, and may be used for the evaluation of palliative systemic-pulmonary artery shunts. In postoperative controls, MR may replace or postpone angio-cardiography. MR is also a promising technique for the evaluation of myocardial and valvular function. Especially in small children, the non-invasive nature of MR is of great importance.

Child, Preschool↗
PubMed1990

[Magnetic tomography at Rikshospitalet].

During the first 18 months of operation of the magnetic resonance unit at Rikshospitalet, 1,453 MR examinations have been performed on 1,431 patients. 64% of the time has been devoted to examinations of the central nervous system and spine in children and adults, nine % of the time has been used on non-neuroradiology pediatric patients, while the rest of the time has been spent equally on ear, nose and throat, thoracic (including cardiac) and abdominal examinations in adult patients. The indications for doing MRI at Rikshospitalet are listed and discussed, and it is concluded that MRI has proved to be useful at several conditions in most organ systems. However, the capacity of our single MR unit is much smaller than the need for examinations. The author discusses reasons.

Denmark↗