New stand magnifiers do not meet rated levels of performance

A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'_v) rather than equivalent dioptric power (F_m) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use.     

Localized osteolysis in stable, non-septic total hip replacement

We are reporting four cases of extensive, localized bone resorption adjacent to a rigidly anchored, cemented total hip replacement. None of these hips showed evidence of infection on clinical, bacteriological, or pathological evaluation. The tissue from the regions of osteolysis showed sheets of macrophages and foreign-body giant cells invading the femoral cortices. Abundant methylmethacrylate particulate debris was present in the tissues, but polyethylene wear debris was absent. The histological appearance of this tissue resembled that reported about loosened total hip implants with the exception of the synovial-like layer at the cement surface. The cases reported here show that aggressive bone lysis may occur around stable cemented total hip arthroplasties without the presence of sepsis or malignant disease.     

Interaction between insulin and glucose-delivery route in regulation of net hepatic glucose uptake in conscious dogs

In the presence of fixed basal levels of insulin, the route of intravenous glucose delivery (protal vs. peripheral) determines whether net hepatic glucose uptake (NHGU) occurs. Our aims were to determine if the route of intravenous glucose delivery also plays a role in regulating NHGU in the presence of hyperinsulinemia and to determine if length of fast (18 vs. 36 h) influences regulation of NHGU. Five conscious dogs fasted 18 h were given somatostatin and replacement insulin (245 +/- 34 microU.kg-1.min-1) and glucagon (0.65 ng.kg-1.min-1) infusions intraportally. After a 40-min control period, the insulin infusion rate was increased fourfold, and glucose was infused for 3 h. Glucose was given either through a peripheral vein or the portal vein for 90 min to double the glucose load reaching the liver. The order of infusions was randomized. NHGU was measured with the arterial - venous difference technique. Insulin and glucagon levels were 12 +/- 2, 35 +/- 6, and 36 +/- 5 microU/ml and 55 +/- 12, 61 +/- 13, and 59 +/- 7 pg/ml during the control, peripheral, and portal infusions, respectively. The glucose infusion rate, the load of glucose reaching the liver, and the arterial-portal plasma glucose gradient were 0, 9.58 +/- 2.28, and 10.44 +/- 2.94 mg.kg-1.min-1; 29.4 +/- 3.6, 56.8 +/- 3.4, and 56.8 +/- 2.8 mg.kg-1.min-1; and 2 +/- 1, 5 +/- 1, and -51 +/- 15 mg/dl during the same periods.(ABSTRACT TRUNCATED AT 250 WORDS)     

A prophylactic bolus of thiopentone does not protect against prolonged focal cerebral ischaemia

Barbiturate coma is still recommended for brain protection during periods of temporary focal ischaemia such as during carotid endarterectomy. We tested the hypothesis that a single dose of barbiturate given before a period of protracted severe focal ischaemia would protect against focal cerebral infarction. Sixteen cats had the proximal left middle cerebral artery (MCA) occluded. Eight cats received halothane alone titrated to keep their pulse and blood pressure within the normal range. Eight cats received, in addition to halothane, a bolus of thiopentone sufficient to produce an isoelectric EEG immediately prior to MCA occlusion. Six hours after the occlusions the animals were sacrificed and the brains scored histologically to assess both size and severity of ischaemia. There was no statistically significant difference in the size or severity of the infarcts between the groups. We conclude from this study that the extent of the histological injury was not reduced by a single prophylactic bolus of thiopentone given before prolonged focal cerebral ischaemia.     

Reaction of chromium (VI) with hydrogen peroxide in the presence of glutathione: reactive intermediates and resulting DNA damage

The reaction of chromium(VI) with hydrogen peroxide was studied in the presence of glutathione. In vitro, reaction of chromium(VI) with hydrogen peroxide alone led to production of hydroxyl radical as the significant reactive intermediate, while reaction of chromium(VI) with glutathione led to formation of two chromium(V)-glutathione complexes and the glutathione thiyl radical. Incubation of chromium(VI) with glutathione prior to addition of hydrogen peroxide led to formation of peroxochromium(V) species and a dramatic increase in hydroxyl radical production over that detected in the reaction of chromium(VI) with hydrogen peroxide alone. In contrast, addition of chromium(VI) to a preincubated mixture of glutathione and hydrogen peroxide led to a decrease in hydroxyl radical production over that obtained in the reaction of chromium(VI) with hydrogen peroxide. When pBR322 DNA was added to the above reactions, the extent of chromium(VI)-induced DNA strand breakage correlated with the relative amount of hydroxyl radical formed. Reaction of chromium(VI) with calf thymus DNA in the presence of a preincubated mixture of glutathione and hydrogen peroxide led to detection of the 8-hydroxydeoxyguanosine adduct, whose formation correlated with that of hydroxyl radical production. No significant chromium-DNA adduct formation was detected. The results suggest that, in the cellular metabolism of chromium(VI), preformed chromium(V)-glutathione complexes may react with hydrogen peroxide in a Fenton-type manner to produce hydroxyl radical as the DNA-damaging agent. However, if glutathione reacts with hydrogen peroxide prior to exposure to chromium(VI), the amount of hydroxyl radical generated may not be sufficient to cause significant DNA damage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Posterior beam-stop method for scatter fraction measurement in digital radiography.

The authors presented a new posterior beam-stop (PBS) technique for measuring the ratio of scattered to total-detected photon flux (scatter fraction) in a radiographic examination while preserving the diagnostic quality of the image. The scatter measurement was made using a standard imaging geometry with both beam stops and an additional x-ray detector placed behind the standard imaging detector. This PBS geometry differs from the standard beam-stop (SBS) technique for scatter measurement. With SBS, a beam-stop shadow appears on the image. To evaluate the PBS technique, scatter fraction measurements were performed on an anatomic phantom using both the PBS and SBS techniques. When compared with the standard technique, PBS provided accurate estimation of scatter fractions. Since the measurement can be performed without degrading a standard clinical radiographic examination, the PBS technique allows simultaneous acquisition of scatter measurements from human patients in combination with a standard radiographic examination.     

P300 and the Risk for Alcoholism: Family History, Task Difficulty, and Gender

P300 event-related brain potentials (ERPs) were obtained from 20 pairs of male and 20 pairs of female undergraduate subjects. One member of each pair reported having a father who was alcoholic (FHP), the other reported no known alcoholic biological relative (FHN). Pair members were matched on age, height, weight, grade point average, and personal drinking history. Three auditory tasks which differed in stimulus discrimination difficulty were presented to each subject. All tasks employed 20% target and 80% standard tones with the subject required to move their index finger whenever a target stimulus was detected. No significant differences in P300 amplitude or latency were obtained between the family history subject groups, although female FHP subjects tended to have smaller P300 amplitudes than their FHN counterparts. P300 amplitude decreased with increases in the amount of self-reported alcohol consumed for FHP subjects but significantly so only for the most difficult task situation. The results suggest that the relationship between the P300 ERP and the inheritability of alcoholism is not yet clear and may be subject to modulation by task requirements, population differences, and subject sex.     

Autoimmune diseases in pregnancy.

Autoimmune diseases are a significant problem in women of reproductive age. This article reviews some of the more common autoimmune disorders and discusses their diagnosis and management during pregnancy. The effects of the autoimmune disorder on pregnancy and the effects of pregnancy on the course of the autoimmune disorder are also discussed with an emphasis on the implications for clinical management.     

Benzazepinone calcium channel blockers. 2. Structure-activity and drug metabolism studies leading to potent antihypertensive agents. Comparison with benzothiazepinones.

As part of a program to discover potent antihypertensive analogues of diltiazem (3a), we prepared 1-benzazepin-2-ones (4). Benzazepinones competitively displace radiolabeled diltiazem, and show the same absolute stereochemical preferences at the calcium channel receptor protein. Derivatives of 4 containing a trifluoromethyl substituent in the fused aromatic ring show potent and long-acting antihypertensive activity. Studies of the metabolism of 4 lead to the metabolically stable antihypertensive calcium channel blockers 5a and 5c. Benzazepinone 5a is a longer acting and more potent antihypertensive agent than the second generation diltiazem analogue TA-3090 (3e).