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Biomedical subjects

J R Todd

Publications and source records attributed to J R Todd.

At least 19 recordsLinked to original sources
PubMed1995

Non-neoplastic chorioretinal enhancement patterns in magnetic resonance imaging of the eye.

OBJECTIVE: To define the role of contrast-enhanced magnetic resonance imaging (MRI) as a possible adjunct to funduscopy and ultrasonography in a selected sample of non-neoplastic disorders of the chorioretina. PATIENTS AND METHODS: The study group consisted of five patients (ranging in age from 3 to 78 years) with one of the following diagnoses: ocular toxocariasis, staphyloma, glaucoma, or ocular involvement of cytomegalovirus (CMV) infection or AIDS. All of the patients underwent MRI, and the findings were correlated with those of funduscopy and ultrasonography when possible. RESULTS: There were two abnormal MRI enhancement patterns, one with and the other without major distortion of the chorioretina. Areas of abnormal enhancement correlated well with the funduscopic findings. For the patient with CMV infection and the one with AIDS, who were not examined with ultrasonography, MRI showed subtle chorioretinal abnormalities. In the other three cases, for which both ultrasonography and MRI were performed, the findings of the two methods correlated well. CONCLUSIONS: Ultrasonography remains the imaging modality of choice in the work-up of most ocular abnormalities. Ultrasonography, MRI and computed tomography are recommended when funduscopy is technically not possible. Because contrast-enhanced MRI is often performed to define the remainder of the orbit, as well as extra-orbital structures, and because of its capability to demonstrate abnormalities of the chorioretina, this modality may serve as a useful adjunct to ultrasonography. Further studies are needed to compare the efficacy of contrast-enhanced MRI and ultrasonography in the evaluation of small, nonneoplastic lesions of the chorioretina.

Adult↗
PubMed1992

Alterations in the microbial flora and in the incidence of bacteremia at a university hospital after adoption of amikacin as the sole formulary aminoglycoside.

Because of the rapid emergence of resistance to gentamicin and tobramycin among isolates of aerobic and facultative gram-negative bacteria at our university hospital, we designed a prospective study to track aminoglycoside resistance, bacteremic episodes, and bacteremia-associated deaths before and after the institution of amikacin as the sole formulary aminoglycoside. From June 1984 through June 1987 (immediately before this policy change), amikacin accounted for only 20% of patient-days of aminoglycoside therapy, and rates of resistance to gentamicin, tobramycin, and amikacin among aerobic and facultative gram-negative bacterial isolates were 12.8%, 10.8%, and 5.9%, respectively. During the next 30 months (immediately after the change in policy), amikacin accounted for 98% of patient-days of aminoglycoside therapy, and rates of resistance to gentamicin, tobramycin, and amikacin were 6.3%, 5.0%, and 3.3%, respectively. Furthermore, during the latter 30 months, the incidence of both bacteremia and bacteremia-associated death decreased significantly. Hospitals at which resistance to gentamicin or tobramycin is increasing among the gram-negative flora may benefit from the use of amikacin as the principal aminoglycoside.

Amikacin↗
PubMed1988

Leprosy in six isolated residents of northern Louisiana. Time-clustered cases in an essentially nonendemic area.

Northern Louisiana has been essentially free of indigenous leprosy, and now it is not. Six new cases of leprosy have been diagnosed: three in 1986, the other three in 1985, 1983, and 1982, respectively. The patients had been lifelong residents of six scattered rural parishes. Leprosy had never been reported from five of them. No patient had had contact with human leprosy. The patients were white; four were women; the mean +/- SD age at onset was 60.3 +/- 16.4 years (age range, 31 to 80 years); and the mean +/- SD interval to diagnosis was 1.2 +/- 1.4 years. One patient had Hodgkin's disease at the age of 25 years and leprosy at the age of 31 years; another patient had cervical carcinoma. All rural northern Louisiana residents coexist with armadillos (Dasypus novemcinctus), some of which are infected with Mycobacterium leprae, the significance of which is unknown. Hypothetically, exposure to an unknown human case, reactivation of "asymptomatic" leprosy through immunosenescence or immunosuppression, or infection from an environmental source might have occurred. Because the patients lacked contact, travel, residence, and exposure risk factors, the origin of leprosy in the new indigenous cases is noteworthy and is not understood.

Adult↗
PubMed1987

Wegener granulomatosis and trimethoprim-sulfamethoxazole. Complete remission after a twenty-year course.

Wegener granulomatosis was diagnosed in a 42-year-old woman in 1965. Although a regimen of azathioprine and prednisone was helpful, the disease progressed. Cyclophosphamide was added to this regimen in 1969. On three separate occasions her disease relapsed when cyclophosphamide therapy was discontinued. In 1984, she developed cyclophosphamide-resistant disease and drug toxicity. We were able to discontinue cyclophosphamide therapy after a trimethoprim-sulfamethoxazole regimen that was begun in February 1985 led to rapid improvement, a fall in the erythrocyte sedimentation rate, and a complete remission. Her 22-year survival is the longest one reported. Because patients with Wegener granulomatosis sometimes respond to trimethoprim-sulfamethoxazole, this therapy deserves careful study and implies that Wegener granulomatosis is an as yet unidentified infection.

Blood Sedimentation↗
PubMed1976

The copper status of beef cattle in Northern Ireland.

1. Serum caeruloplasmin (ferroxidase I;EC 1.16.3.1) activity has been used as an indicator of copper status of cattle to survey beef herds in Northern Ireland. 2. The main survey covered some 20 000 cows on 1200 farms. 3. The results are reported in the form of a map showing area where herds of low and very-low Cu status predominate. Clinical signs of Cu deficiency in calves were encountered in only two areas.

Animals↗
PubMed1976

Role of pentose-phosphate pathway in haemolytic crisis of chronic copper toxicity of sheep.

Although the rise in blood copper is associated with onset of the acute haemolytic crisis of chronic copper poisoning in sheep, the sudden fall in erythrocyte glutathione is apparently not due to a direct action of the copper. Moreover the reduced glutathione of the red cells is converted to some form that is not capable of regeneration by the pentose-phosphate mechanism. Only negligible inhibition of the pentose-phosphate enzymes occurs. As the haemolysis proceeds, there is a rapid recovery of erythrocyte glutathione levels, and a marked increase in pentose-phosphate enzyme activity, consistent with influx of young red cells. It seems that the release of copper into blood from liver at the haemolytic crisis is associated with an increase of the oxidative state of the blood, possibly by simultaneous release of other components from the liver.

Animals↗