Cytochrome c oxidase in Neurospora crassa contains myristic acid covalently linked to subunit 1.

Radiolabel from [3H]myristic acid was incorporated by Neurospora crassa into the core catalytic subunit 1 of cytochrome c oxidase (EC 1.9.3.1), as indicated by immunoprecipitation. This modification of the subunit, which was specific for myristic acid, represents an uncommon type of myristoylation through an amide linkage at an internal lysine, rather than an N-terminal glycine. The [3H]myristate, which was chemically recovered from the radiolabeled subunit peptide, modified an invariant Lys-324, based upon analyses of proteolysis products. This myristoylated lysine is found within one of the predicted transmembrane helices of subunit 1 and could contribute to the environment of the active site of the enzyme. The myristate was identified by mass spectrometry as a component of mature subunit 1 of a catalytically active, purified enzyme. To our knowledge, fatty acylation of a mitochondrially synthesized inner-membrane protein has not been reported previously.     

Pre- vs postoperative pharmacologic inhibition of platelets: effect on intimal hyperplasia in canine autogenous vein grafts.

Several clinical studies have shown that pharmacologic inhibition of platelets can increase the patency of vascular grafts, but only if platelet-inhibition is initiated before surgery. This study was performed to compare the efficacy of pre- vs postoperative platelet-inhibition on the development of intimal hyperplasia in canine autogenous vein grafts. Reversed femoral veins were used to bypass the ligated femoral arteries in 15 dogs. End-to-side anastomoses were constructed. Eleven dogs were treated with aspirin (325 mg QD) and dipyridamole (25 mg BID). In six dogs treatment was begun 48 hours preoperatively and continued for 3 months. In five other dogs treatment was begun 48 hours after surgery and was continued for 3 months. In 4 control dogs no antiplatelet treatment was given. Excision of the vein grafts 3 months after surgery disclosed reduced intimal hyperplasia (p < 0.05) in the grafts excised from all of the treated animals as compared with those obtained from the control animals. However, there was no difference in intimal hyperplasia observed in the dogs treated both pre- and postoperatively (11 grafts) as compared with those treated only postoperatively (9 grafts). These data demonstrate that it is not necessary to begin antiplatelet therapy preoperatively in order to inhibit intimal hyperplasia. They also suggest that preoperative antiplatelet therapy may improve early graft patency by directly preventing thrombosis, not by inhibiting the development of intimal hyperplasia.     

Length and width summation in human vision at different background levels

Summary The effect of background intensity on the spatial summation of rectangular stimuli of varying length and width was studied in human psychophysical experiments and compared with the known effects of light adaptation on the spatial summation of circular stimuli. Both the detection threshold and the threshold of orientation identification were measured. In agreement with previous data, summation was more efficient along the line stimulus than across it. This asymmetry was found to exist at all adaptation levels studied (1–1000 trolands). The adaptation level affected both length and width summation; the change in the length of summation was twice as great as the change in the diameter of summation with circular stimuli. Orientation selectivity was reduced for short lines presented on a dim background. The results suggest the existence of mechanisms of light adaptation at the level of cortical orientation-selective units.     

Changing aspects of psychiatric inpatient treatment

This paper presents data obtained in a one-day census investigation in five European countries (Austria, Hungary, Romania, Slovakia, Slovenia). The census forms were filled in for 4191 psychiatric inpatients. Concerning legal status, 11.2% were hospitalised against their will (committed) and 21.4% were treated in a ward with locked doors. There was only a small correlation between commitment and treatment in a locked ward. More frequent than treatment of committed patients in locked wards was treatment of committed patients in open wards (Austria, Hungary) and treatment of voluntary patients in closed wards (Slovakia, Slovenia). Concerning employment, 27.7% of patients aged 18-60 held a job before admission. The vast majority of patients (84.8%) had a length of stay of less than 3 months. A comparison of these data with the results of a study performed in 1996 and using the same method shows a decrease of rates of long-stay patients. In 1996 the rates of employment were significantly higher in Romania (39.3%) and Slovakia (42.5%) compared to Austria (30.7%). These differences disappeared in 1999 due to decreasing rates of employment in Romania and Slovakia. The numbers of mental health personnel varies between types of institution (university or non-university) and countries, being highest in Austria and lowest in Romania. A considerable increase in the numbers of staff was found in Slovakia.     

Balloon embolectomy catheters in small arteries: a technique to prevent excessive shear forces

Balloon embolectomy catheters were studied in canine common carotid arteries (2 to 3 mm) in vitro to evaluate a technique of preventing excessive shear forces and to examine the effect of blood within the lumen. Each balloon was studied at 25, 75, 125, or 150 mm Hg lateral wall pressure. Shear forces were recorded in 16 vessels when the balloons were distended before catheter withdrawal, and these data were compared with forces recorded when the balloons were distended during catheter withdrawal. Results showed that distention of the balloon during withdrawal reduced shear forces 43.8% to 55.8% (p less than 0.05). In other experiments shear forces were recorded when the lumen was lubricated with heparinized saline solution, and these were compared with forces recorded when the lumen was lubricated with heparinized whole blood. The presence of blood in the lumen reduced shear forces 23.4% to 52.9% (p less than 0.05). From these studies it is recommended that during embolectomy in patients the balloons be distended during the first half centimeter or centimeter of catheter withdrawal to prevent excessive shear forces and that residual blood in the vessel lumen proximal to the point of embolic obstruction be accepted without concern, provided adequate heparinization has been achieved.     

Adaptation to square-wave gratings: In search of the elusive third harmonic

Blakemore andCampbell (1969) found that a square-wave adapting grating, unlike a sinewave grating of the same period, elevates threshold contrast for test gratings whose frequency is in the vicinity of the third harmonic in the square-wave. Because of its important bearing on the frequency-specificity of adaptation to gratings, we attempted to replicate this finding. Our attempt was successful with one of two observers when the method of adjustment was used to determine thresholds. With the temporal two alternative, forced-choice method, individual differences in this regard disappeared. For all three observers a 3 c/deg adapting square-wave and a 3 c/deg sinewave were equally ineffective in raising the contrast threshold for a 9 c/deg test grating, whereas a 9 c/deg adapting grating, matched to the 3rd harmonic in the square-wave, raised the test grating's threshold by 0.2 log units. Our failure to find consistent evidence that the third harmonic in a square-wave does any adapting whatever casts doubt on the frequency-specificity of adaptation to gratings.