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Biomedical subjects

N Farid

Publications and source records attributed to N Farid.

14 recordsLinked to original sources
PubMed1998

Abnormalities of retinal metabolism in diabetes or experimental galactosemia: V. Relationship between protein kinase C and ATPases.

In the retinas of diabetic animals, protein kinase C (PKC) activity is elevated, and Na+-K+-ATPase and calcium ATPase activities are subnormal. These abnormalities are also present in another model of diabetic retinopathy, experimental galactosemia. We have investigated the relationship between hyperglycemia-induced abnormalities of PKC and ATPases using a selective inhibitor of beta isoform of PKC (LY333531). Diabetes or experimental galactosemia of 2 months' duration resulted in > 50% elevation of PKC activity in the retina, and administration of LY333531 prevented the elevation. In retinas of the same rats, the LY333531 prevented hyperglycemia-induced decreases of both Na+-K+-ATPase and calcium ATPase activities. Retinal microvessels, the main site of lesions in diabetic retinopathy, likewise showed elevated activity of PKC and inhibition of ATPases in diabetes and in experimental galactosemia, and administration of LY333531 to diabetic animals prevented these abnormalities. PKC activity in sciatic nerves, in contrast, became subnormal in diabetes and experimental galactosemia, and LY333531 had no effect on PKC activity in the sciatic nerve. PKC activity in the cerebral cortex was not affected by diabetes or experimental galactosemia. The results suggest that diabetes-induced reductions in Na+-K+-ATPase and calcium ATPase in the retina are mediated in large part by PKC-beta. The availability of an agent that can normalize the hyperglycemia-induced increase in PKC activity in the retina should facilitate investigation of the role of PKC in the development of diabetic retinopathy.

Animals↗
PubMed1994

[Angioscopic evaluation of the immediate result of coronary angioplasty in relation to balloon inflation time].

The aim of this study was to assess the effects of coronary angioplasty on the intima with respect to the duration of balloon inflation by percutaneous angioplasty. Twenty-seven patients were randomized according to the total duration of balloon inflation: Group I "standard" duration (total duration < or = 3 min, N = 13) and Group II: prolonged duration (total duration > or = 12 min, N = 14); the type and distribution of the lesions were comparable in the two groups. The results of angioplasty were evaluated immediately after dilatation by angiography and angioscopy. Angioscopy was performed without failure or complications with perfect definition of the images in all cases. Angioscopy showed 1) intimal tears, 2) thrombi, 3) longitudinal dissections. A classification in three grades was used taking the apparent gravity of the lesions into consideration. The mean duration of balloon inflation in Group I was 205 +/- 45 s and 958 +/- 129 s in Group II. The residual stenosis was 36 +/- 8% in Group I and 26 +/- 10% in Group II (p < 0.05). Angioscopy showed the frequency of intimal tears to be twice greater in Group I (9 cases) than in Group II (4 cases) (p = 0.05). Intravascular thrombi were observed in 13 cases, 6 in Group I and 7 in Group II. One case of longitudinal dissection was observed in each group: only one of these two cases was detected at angiography. The authors conclude that repeated and prolonged balloon inflations improve the immediate results of angioplasty with less residual stenosis at angiography and a lower incidence of intimal tears at angioscopy.

Aged↗
PubMed1994

Mapping the gene for hereditary hyperparathyroidism and prolactinoma (MEN1Burin) to chromosome 11q: evidence for a founder effect in patients from Newfoundland.

An autosomal dominant syndrome of prolactinomas, carcinoids, and hyperparathyroidism was described in four Newfoundland kindreds in 1980 and in one kindred from the Pacific Northwest in 1983. Because this syndrome shares many features with multiple endocrine neoplasia type 1, the gene for which maps to proximal chromosome 11q, we performed linkage studies with chromosome 11 markers in prolactinoma families to determine whether the two genes map to the same location. All proximal chromosome 11q markers gave positive LOD scores, and no recombinants were seen with PYGM (LOD score 15.25, recombination fraction .0). All affected individuals from Newfoundland shared the same PYGM allele, providing evidence for a founder effect. The disease in the Pacific Northwest kindred cosegregated with a different PYGM allele.

Base Sequence↗
PubMed1991

A digital splenoportography: more sensitive method of detecting spontaneous splenorenal shunt.

Splenoportography was performed upon 195 pediatric patients, including 137 by conventional technique and 58 by digital subtraction technique. The results obtained were compared, and it was found that the percentage of diagnosis of spontaneous splenorenal shunt was higher with digital than with conventional technique. In conclusion digital technique is a more sensitive and safer method than the conventional method.

Angiography, Digital Subtraction↗
PubMed1989

Contrast material-induced renal failure in patients with diabetes mellitus, renal insufficiency, or both. A prospective controlled study.

To determine the risk of nephrotoxicity induced by the infusion of radiographic contrast material, we undertook a prospective study of consecutive patients undergoing radiographic procedures with intravascular contrast material. There were three study groups: patients with diabetes mellitus and normal renal function (n = 85), patients with preexisting renal insufficiency (serum creatinine level, greater than or equal to 150 mumol per liter) without diabetes (n = 101), and patients with both diabetes and renal insufficiency (n = 34). The control group consisted of patients undergoing CT scanning or abdominal imaging procedures without the infusion of contrast material who had diabetes mellitus (n = 59), preexisting renal insufficiency (n = 145), or both (n = 64). Clinically important acute renal failure (defined as an increase of greater than 50 percent in the serum creatinine level) attributable to the contrast material did not occur in nondiabetic patients with preexisting renal insufficiency or in diabetics with normal renal function. The incidence of clinically important contrast-induced renal failure among the diabetic patients with preexisting renal insufficiency was 8.8 percent (95 percent confidence interval, 1.9 to 23.7 percent), as compared with 1.6 percent for the controls. The incidence of acute renal insufficiency, more broadly defined as an increase of greater than 25 percent in the serum creatinine level after the infusion of contrast material, was 11.8 percent among all patients with preexisting renal insufficiency. After the exclusion of patients whose acute renal insufficiency could be attributed to other causes, the incidence was 7.0 percent (95 percent confidence interval, 3.2 to 12.8 percent), as compared with 1.5 percent in the control group. The risk of acute renal insufficiency attributable to the contrast material was therefore 5.5 percent, and the relative risk associated with the infusion of contrast material was 4.7. These rates were similar whether the osmolarity of the contrast material was high or low. We conclude that there is little risk of clinically important nephrotoxicity attributable to contrast material for patients with diabetes and normal renal function or for nondiabetic patients with preexisting renal insufficiency. The risk for those with both diabetes and preexisting renal insufficiency is about 9 percent, which is lower than previously reported.

Clinical Trials as Topic↗
PubMed1988

Sonographic and urographic correlation in Bardet-Biedl syndrome (formerly Laurence-Moon-Biedl syndrome).

To determine the spectrum of urologic disease and the value of ultrasound as a screening mechanism, renal imaging was performed on 23 patients with Bardet-Biedl syndrome. On intravenous urography (IVU), abnormal calices were present in 22 patients, with communicating cortical cysts/diverticula in 17. Ultrasound detected caliceal or cystic changes in 70%. On IVU, 21 patients had fetal-type lobular outlines that were detected on sonography in 95%. Renal structural abnormalities are characteristic of the Bardet-Biedl syndrome, and are still best imaged by urography.

Adolescent↗
PubMed1988

Evidence for an adrenal contribution to plasma digitalis-like factors.

Digitalis-like factors (DLF) were assayed on plasma collected serially using antibody to digoxin: (1) after intravenous ACTH (n = 3 patients) and (2) after 0.15 U/kg crystalline insulin, 50 micrograms gonadotropin-releasing hormone and 0.2 mg thyrotropin-releasing hormone (n = 7) as a combined pituitary function test. Patients had either hypothalamic-pituitary or ovarian problems. Mean values for DLF rose fourfold after ACTH, and by a factor of 2.3 with the combined pituitary function test. DLF rose at least 50% in all 10 subjects. In 3 dogs, adrenal vein values for DLF were on average more than double values in either adrenal artery or lower vena cava. These results suggest that certain DLFs have an adrenal origin.

Adrenal Glands↗
PubMed1986

Class III alleles and high-risk MHC haplotypes in type I diabetes mellitus, Graves' disease and Hashimoto's thyroiditis.

By typing a large quantity of family-based material for HLA-B, HLA-DR, C4, C2 and factor B, we were able to derive four-gene complement haplotypes (C4A, C4B, C2, BF) and six-gene MHC haplotypes (HLA-B, complement, HLA-DR). Fourteen six-gene MHC haplotypes showed linkage disequilibrium but exact frequencies could not be determined because it was not always possible to assign null C4 alleles in families where null genes were not clearly seen to segregate. Comparison of unrelated type I diabetes, Graves' disease and Hashimoto's thyroiditis patients with healthy unrelated controls revealed the following MHC allele associations: C4B*3, HLA-DR3 and HLA-DR4 with type I diabetes; BF*F1 and HLA-DR3 with Graves' disease; HLA-DR4 with Hashimoto's thyroiditis. By typing families of type I diabetes and Graves' disease patients we were able to derive two high-risk DR3+ MHC haplotypes for both type I diabetes and Graves' disease. These are HLA-B8 C4A*Q0 C4B*1 BF*S HLA-DR3 and HLA-B18 C4A*3 C4B*Q0 BF*F1 HLA-DR3, and these haplotypes account for most of the associations between these diseases and HLA-DR3. The MHC haplotype HLA-B15 C4A*3 C4B*3 BF*S HLA-DR4 also carries high risk for type I diabetes in this group of patients. Our data suggest that other DR4+ haplotypes, probably containing C4A*3 C4B*1, carry increased risk for type I diabetes whereas haplotypes containing DR4 and C4 C4A*3 C4B*Q0 do not. Our phenotype data suggest that DR4 in Hashimoto's thyroiditis is frequently associated with HLA-B44, C4A*3, C4B*1 and BF*S.

Alleles↗
PubMed1985

Clinical pharmacology of tomoxetine, a potential antidepressant.

Tomoxetine (LY139603) selectively inhibits norepinephrine uptake in animals and has activity in animal models of depression. Tomoxetine was administered in single oral doses up to 90 mg to healthy normal volunteers. In addition, normal human subjects received either 20 or 40 mg of tomoxetine b.i.d. for 1 week to evaluate the safety and pharmacologic activity of the compound in humans. At these doses, no serious drug-related adverse effects were encountered. Activity of the compound at the lower dose (20 mg b.i.d.) was evaluated by examining changes in the pressor responses to infused norepinephrine and tyramine and by determining [3H]serotonin uptake in platelets harvested from subjects receiving the compound. Pressor sensitivity to norepinephrine was increased by 261 +/- 69% of control, and pressor sensitivity to tyramine was decreased by 51 +/- 6% of control during treatment. Changes in the pressor sensitivity to norepinephrine in individual subjects were positively correlated with drug levels. There were no statistically significant changes in platelet [3H]serotonin uptake. These results indicate that tomoxetine selectively inhibits norepinephrine uptake in humans at doses which are clinically well tolerated and suggest that tomoxetine has potential clinical use as an antidepressant.

Adult↗