Ni/Si-Based Ohmic Contacts to p- and n-Type GaN

Ni/Si-based ohmic contact scheme for GaN, based on the solid-phase regrowth (SPR) mechanism have been developed. Using Mg and Si as dopant species, ohmic contacts with a resistivity of ∼1*10-3Ωcm2 to p-GaN (p≈3*1017 cm-3) and n-GaN (n≈2*1017cm-3), respectively, have been obtained. SIMS, XRD, and RBS analysis show in as-deposited contacts, an initial reaction at GaN/Ni interface, leading to the formation of an Ni-Ga-N layer. The ohmic behavior of contacts, observed after annealing at 400°C, is accompanied by structural transformations in the contact region: i) the decomposition of Ni-Ga-N layer and ii) the growth of NiSi compound.

MR CSF Flow Examination as a Non-Invasive Method of Determining Shunt-Independent Hydrocephalus in Children with Implanted Ventriculoperitoneal Shunt

The study discusses the value of MR examination of CSF flow through the cranial part of the ventriculoperitoneal shunt in the evaluation of shunt-dependent hydrocephalus. Sixteen patients aged eight to 18 years were examined in the course of many years of treatment using the ventriculoperitoneal shunt. No clinical manifestations of shunt obstruction had been observed in any of the patients prior to MR examination. A Signa Horizon 1.5T (GEMS) unit was used. Axial and sagittal T1- and T2-weighted images were performed to find the ventriculoperitoneal shunt canal. A 2D CINE/GR/PC sequence was performed in the plane perpendicular to the shunt canal. CSF-flow was calculated by the Flow Analysis program. Patients were divided into two groups: 1) no CSF-flow was noted in five children indicating shunt-independent hydrocephalus; 2) CSF-flow was present (average flow volume from 0.1 to 1.9 ml/min) in 11 children, distinguishing the group with shunt-dependent hydrocephalus. Conclusions: 1) MR CSF flow examination will establish the absence or presence of CSF flow and determine its direction and velocity. 2) With no clinical manifestations of shunt impatency the absence of flow in the shunt canal found in MR CSF flow examination may indicate shunt-independent hydrocephalus. 3) When the CSF flow in the shunt is found in MR shunt-dependent hydrocephalus is diagnosed.

The activity of erythrocyte sodium-proton exchanger in women with pregnancy- induced hypertension

BACKGROUND

Hypertension that develops after 20 gestational weeks and is defined as pregnancy-induced hypertension (PIH). The main cause of PIH is vasoconstriction and the thickening of vascular media, which decreases vascular capacity and increases peripheral resistance. One of the theories postulated to explain this phenomenon is that a transmembrane sodium transport disorder causes an increase in intracellular sodium concentration. In the latest literature, special attention is paid to the role of the increased intracellular sodium concentration in the pathogenesis of essential hypertension (EH). One of the best documented phenotypes for EH is the increased activity of the sodium-proton exchanger (NHE). The aim of this study was to assess if increased NHE activity could be the mechanism responsible for the development of PIH.

SUBJECTS AND METHODS

The study included 30 women: 10 pregnant women with PIH after gestational week 30, 10 women with physiological pregnancy after 30 gestational weeks, and 10 healthy non-pregnant women. NHE activity was determined according to Orlov's method as amiloride-sensitive H(+) efflux from acid-loaded cells.

RESULTS

The NHE activity in the group of women with PIH was significantly higher than that in women with physiological pregnancy: 10.09 +/- 1.65 vs. 6.81 +/- 2.3 mmol/L RBC/h (p < 0.049) and in the group of non-pregnant women: 10.09 +/- 1.65 vs. 7.56 +/- 1.66 mmol/L RBC/h (p < 0.029). Erythrocyte NHE activity did not differ in the group of women with physiological pregnancy and in the group of non-pregnant women.

CONCLUSION

These results seem to suggest that erythrocyte NHE activity is elevated in PIH pregnancies.

Blood and tissue selenium concentrations and glutathione peroxidase activities in patients with prostate cancer and benign prostate hyperplasia

Prostate cancer (PC) is the most common cancer in men and a leading cause of cancer death. Prostatic gland accumulates reasonably high amount of selenium (Se), the element that prevents the development of PC. It is hypothesized that some selenoproteins inhibit the transformation of normal prostate epithelium into neoplasm. We studied Se levels in whole blood, plasma and prostate of 32 PC and 40 benign prostate hyperplasia (BPH) patients and in the control group composed of 39 healthy subjects. The selenoenzyme glutathione peroxidase (GSH-Px) was also measured in the patients' red cells, plasma and prostate tissue. Se concentration in whole blood and plasma in both groups of patients was lower as compared with controls, while in prostate gland it was significantly higher in PC than in BPH patients and controls. Red cell GSH-Px activity was the same in PC patients and controls but significantly lower in BPH patients. Plasma GSH-Px activity was significantly lower in PC patients than in the control group, and prostate GSH-Px activity was significantly lower in PC patients as compared with BPH patients. Since Se has anticancer properties, it is very likely that its low level in blood may facilitate the development of cancer. A higher level of Se in prostate of PC patients has no influence on GSH-Px activity in the gland.

[Suprasellar arachnoidal cysts as cause of precocious puberty]

The paper presents the clinical picture, diagnostic and therapeutic management of suprasellar arachnoid cysts that result in isosexual precocious puberty in children. The authors stress the importance of physical examinations involving routine assessment of growth and sexual development as well as neurological evaluation in early diagnosis of suprasellar arachnoid cysts and other central causes of precocious puberty. The role of early diagnosis in preventing irreversible somatic and mental changes is emphasized.

[Spontaneous spinal epidural hematoma. Report of two cases]

In the paper 2 cases of non-traumatic spinal epidural haematomas are presented. The possible aetiological factors--vascular malformation, coagulopathy, anticoagulants and neoplasm are discussed. Neurological state, diagnostic procedure and treatment are described. Taking into account our experience we state that only early diagnosis and operation-surgical decompression of spinal cord, could result in complete recovery.

[Piracetam in severe cranio-cerebral injuries]

A group of 100 patients treated immediately following a cranio-cerebral injury was analyzed. The patients, administered piracetam either in an intravenous infusion (GCS 3-8) or orally (GCS above 9), were divided into groups depending on the dose and clinical status. Piracetam participates in the activity of the majority of neurotransmitters, increases glucose and oxygen consumption in the ischaemic nervous tissue and increases blood flow through cerebral terminal vessels. In cranio-cerebral injuries, piracetam is employed to achieve cytoprotection and improve cerebral blood flow. In patients with neurological deterioration following the administration of 6-10 mg/day, no good results were obtained. A dose of 24-30 mg/day had a significant positive effect on therapeutic results providing certain conditions were met, such as ensuring proper partial oxygen pressure (oxygen therapy) and proper blood glucose levels. The use of piracetam is justified immediately after an injury; after the discharge oral piracetam therapy is recommended.

Effectiveness of a nurse-managed follow-up program for rehabilitation patients after discharge

Former patients in a rehabilitation unit at a large Midwestern hospital continued to actively seek services provided by the inpatient nursing staff, primarily through telephone contact, long after their discharge. A proactive formal follow-up program managed by an advanced practice nurse in rehabilitation was proposed as a better means of providing continuing care for rehabilitation patients after discharge. To examine the efficacy of the nurse-managed follow-up program, a randomized clinical trial was conducted. One hundred patients were randomly assigned to either the intervention group or the control group. Comparisons were made between the two groups on several outcome measures at 4 months after discharge. Outcomes included Functional Independence Measure (FIM) instrument scores, complication rates, rehospitalizations, and anxiety levels. The organizational outcomes included number and types of calls to staff, as well as time spent by staff nurses and social workers. The results indicated significant differences between the intervention and control groups in terms of anxiety levels, the number of calls made to the unit, and the amount of time spent by staff nurses and social workers.

[Evaluation of nitrate, nitrite and total protein content in selected vegetables cultivated conventionally and ecologically]

Nitrates, nitrites and total protein content in selected vegetables from conventional and ecological farms were estimated. The beetroots, carrots, potatoes available on market or special shops in January, May and March were evaluated. The content of nitrates and nitrites was determined by colorimetric method with Griess reagent after previous reduction of nitrates to nitrites by metallic cadmium. Total protein content was determined by Kjel-Foss Automatic 16210 analyser working on the basis of classical Kjeldahl method. The higher content of nitrates was found in vegetables from conventional farms. Amounts of nitrates in both groups of vegetables did not exceed allowed limits. Levels of nitrites in ecological and conventional vegetables were similar-above 0.5 mg NaNO2/kg (except conventional potatoes from January). Slightly more content of protein was recorded in conventional vegetables.

The Kluver-Bucy syndrome

Evolution of psychological disorders following head injury including memory disorders and other cognitive ones are common. The best known are psychiatric disturbances of various kind after lesions of frontal lobes. Cognitive, behavioural and emotional disorders are not usually seen in patients with bilateral temporal lesions. In our Department of Neurotraumatology we observed 4 patients with post-traumatic lesions localized bitemporally. They developed Kluver-Bucy syndrome--rarity in human pathology--with combination of three or more the following syndromes: increased oral activity, hypersexuality, hypermetamorphosis, memory disorders, placidity, loss of people recognition, bulimia. Several symptoms responded dramatically to carbamazepine. We conclude that it may be a useful agent in treatment of this unusual syndrome.

The Kluver-Bucy syndrome

Evolution of psychological disorders following head injury including memory and other cognitive disorders are common. The best known are psychiatric disturbances of various kinds after lesions of the frontal lobes. Cognitive, behavioural and emotional disorders are not usually seen in patients with bilateral temporal lesions. In our Department of Neurotraumatology we have observed 4 patients with posttraumatic lesions localized bitemporally. They developed Kluver-Bucy syndrome-rarity in human pathology-combined with three or more of the following symptoms and signs: increased oral activity, hypersexuality, hypermetamorphosis, memory disorders, placidity, loss of people recognition, bulimia. Several symptoms responded dramatically to carbamazepine. We conclude that it may be a useful agent in the treatment of this unusual syndrome.

[Autotransfusion in neurotraumatology and neurosurgery]

In the years 1991-1993, 145 patients suffering from central nervous system diseases were operated on using autotransfusion in the Institute of Neurology in Cracow. In 141 cases patients were given blood taken formerly. There were no side effects following blood treatment. In the authors opinion autotransfusion deserves wider use for medical and economic reasons.

Developing and implementing a stroke education series for patients and families

Stroke is the third leading cause of death and the major reason for disability in American adults (Sullivan, 1992). Stroke can be a recurrent disease, but most strokes are preventable. Patient and family education about stroke is a vital link in eliminating the knowledge deficit that can help lead to stroke. This article describes the process of developing and implementing a stroke education program that involves both patients and their significant others. In 1990, rehabilitation nurses at St. Margaret Mercy Healthcare Centers in Hammond, IN, identified 11 essential areas for education and grouped them into six 1-hour teaching sessions. A program was developed and held weekly for a trial period of 3 months. It was so well received that it continues to be a permanent part of the rehabilitation program. Such structured teaching in a relaxed atmosphere better prepares patients for discharge and eases the transition to the home environment.

[Post-traumatic cerebral vasospasms]

Posttraumatic vasospasms occur according to various authors in 5-10% of cases, and in our material they were demonstrated in 6% of the patients, that is about 8 times less frequently than in cases of bleeding from a vascular malformation. Computed tomography of the head showing posttraumatic vasospasm complicating "normal" clinical course is ever less frequent which does not mean that this disturbance is not occurring, but rather it shows that CT is insufficient for its demonstration. It was shown that in every case of unclear aetiology in which the clinical condition is not correlating with CT pattern of the head angiography of brain vessels should be performed or cerebral blood flow should be determined by other making possible early institution of adequate (targeted) treatment.

Immunoassay detection of drugs in racing horses: detection of ethacrynic acid and bumetanide in equine urine by ELISA

We have raised antibodies and developed one-step enzyme-linked immunosorbent assays (ELISA) for the diuretics ethacrynic acid and bumetanide as part of a panel of pre- and post-race tests for high potency drugs in racing horses. These ELISA tests are rapid (completed within one hour), sensitive, and can be read by eye. The ELISA detects ethacrynic acid at a drug concentration for half-maximal inhibition (I-50) of about 2.5 ng/mL for the parent drug. After dosing horses intravenously with 5 mg ethacrynic acid per horse, the parent drug or its metabolites are detectable in urine for at least 8 hours. The bumetanide ELISA has an I-50 for the parent drug of about 2.0 ng/mL and will detect bumetanide or its metabolites for about 8 hours in urine after intravenous administration of a 1.7-mg dose per horse. Both antibodies are relatively specific for each drug and do not cross-react with other commonly used diuretics or other acidic compounds often found in post-race equine urine samples. Ethacrynic acid and bumetanide are potent diuretics suspected of being illegally substituted for furosemide in certain racing jurisdictions. Development of these rapid, sensitive, and simple tests for these agents will allow more effective pre- and post-race control of the use of these agents in racing horses. Both tests have recently uncovered several "positives" for these medications in a midwestern racing jurisdiction.

Esophageal motility in the personnel operating heavy self-propelled mining machines

We examined 47 men exposed to whole-body vibration for a long time (average 9.8 years) and tested esophageal motility. The following parameters were measured: mean pressure in the body of esophagus during the passing of peristaltic wave, maximum value of pressure during the passing of peristaltic wave, mean and maximum duration of spasm and peristaltic wave transmission velocity was calculated. In over 1/4 exposed to whole-body vibration disorders of esophagus motility were observed. These disorders are probably a consequence of vocational exposure to whole-body vibration.

Photolysis of 3-aryl-3-(trifluoromethyl)diazirines: a caveat regarding their use in photoaffinity probes

The photolysis of 3-(4-tolyl)-3-(trifluoromethyl)diazirine in the presence of benzene, methanol, carbon tetrachloride, cyclohexane, triethylsilane, or diethylamine led to photoproducts consistent with the intermediacy of a singlet carbene. In the case of diethylamine, the photoinsertion into the N-H bond of diethylamine produced the expected adduct, 1-(diethylamino)-2,2,2-trifluoro-1-(4-tolyl)ethane. However, the base-catalyzed elimination of hydrogen fluoride from this adduct afforded an enamine, alpha-(diethylamino)-beta,beta-difluoro-4-methylstyrene, and the subsequent hydrolysis of this enamine furnished diethylamine and 2,2-difluoro-1-(4-tolyl)ethanone. This elimination and hydrolysis sequence effectively reversed the photoinsertion process. A similar photoinsertion and hydrolysis process using 3-(4-n-octylphenyl)-3-(trifluoromethyl)diazirine also produced 2,2-difluoro-1-(4-n-octylphenyl)ethanone in modest yield. These results suggest that the photoinsertion products from 3-aryl-3-(trifluoromethyl)-diazirines in biological systems may suffer similar fates limiting, in part, their utility in obtaining primary sequence data.

Heterobifunctional cross-linking agents incorporating perfluorinated aryl azides

New heterobifunctional cross-linking reagents were developed that possess a photoactive tetrafluorinated phenyl azide as the photoactive terminus and a chemically reactive succinimidyl ester as the electrophilic terminus. These reagents, succinimidyl N-(4-azido-2,3,5,6-tetrafluorobenzoyl)tyrosinate (9) and succinimidyl 2-(4-azido-2,3,5,6-tetrafluorophenyl)thiazole-4-carboxylate (15), were designed to possess either an 125I or 35S radiolabel, respectively. In a biochemical study, the latter reagent was coupled to Lys-75 of calmodulin (CaM), and the radioiodinated monoadduct was photochemically cross-linked, in a calcium-dependent manner, to the porcine erythrocyte plasma membrane Ca2+, Mg2(+)-ATPase. Densitometry scans of the gel indicated a reproducible 22% cross-linking of the CaM with one of the Ca2+,Mg2(+)-ATPase bands. Since the purification of the Ca2+,Mg2(+)-ATPase results in micelles having Ca2+,Mg2(+)-ATPase with its CaM binding site oriented both to the inside and outside of the micelle, the amount of Ca2+,Mg2(+)-ATPase available for cross-linking was reduced by approximately half, suggesting that the actual cross-linking efficiency was on the order of 40%.

Immunoassay detection of drugs in racing horses. XI. ELISA and RIA detection of fentanyl, alfentanil, sufentanil and carfentanil in equine blood and urine

We have developed and evaluated a one step enzyme-linked immunosorbent assay (ELISA) test for sufentanil and a 125I radioimmunoassay test for alfentanil as part of a panel of pre- and post-race tests for narcotic analgesics in racing horses. Our sufentanil ELISA test detects sufentanil with an I-50 of about 0.5 ng/ml. The test is rapid and economical in that it can be read with an inexpensive spectrophotometer, or even by eye. The test readily detects the presence of sufentanil or its metabolites in equine blood and urine from 1 to 24 hours respectively after administration of therapeutic or sub-therapeutic doses of this drug. Our sufentanil assay also cross-reacts with fentanyl, the methylated analogs of fentanyl (designer fentanyls), and carfentanil and detected these drugs in urine for several hours after their administration to horses. It does not, however, cross-react significantly with alfentanil. We have also developed an 125I radioimmunoassay for alfentanil. This test allows detection of alfentanil in blood and urine of horses for up to 4 hours after administration of this drug. As such, these tests are capable of improving the quality and reducing the cost of pre-race and post-race testing for fentanyl, sufentanil, carfentanil and alfentanil and a number of their congeners in racing horses. Similarly, these tests are capable of screening for these drugs in human drug abuse monitoring.

A preliminary consideration of the glass-ceramic dowel post and core

Both cast ceramic and metal post and cores were made for endodontically treated extracted teeth and restored with ceramic restorations. The ceramic posts did not change the translucency or color of the natural tooth, in contrast to the metal posts, which altered both. A clinical study followed, with eight restorations placed for a mean period of service of 11.3 months. One ceramic post failed early following cementation. This preliminary report indicates that ceramic posts and cores offer excellent esthetic results and may be strong enough for clinical use under normal conditions.

Non-isotopic immunoassay drug tests in racing horses: a review of their application to pre- and post-race testing, drug quantitation, and human drug testing

We have introduced large scale non-isotopic immunoassay testing into pre- and post-race drug testing in racehorses. The technologies utilized are Particle Concentration Fluorescence Immuno Assay (PCFIA) and the one-step Enzyme Linked Immuno Sorbent Assay (ELISA). These technologies are rapid, inexpensive, and highly effective. On introduction into post-race testing in the Western United States, these ELISA tests exposed several previously undetected patterns of drug abuse. The drugs detected were buprenorphine, oxymorphone, mazindol, sufentanil and cocaine. This led to the suspension of a large number of trainers and exposed the high false negative rate of thin layer chromatography (TLC) based testing. More recently, we have introduced both PCFIA and ELISA assays into pre- and post-race testing in Illinois. Within days, our pre-race PCFIA tests detected signs of acepromazine abuse. Directed searches of post-race urines from these horses showed evidence for acepromazine metabolites in the urine of these horses. Examination of frozen samples from associated horses yielded about 70 ELISA "positives" for acepromazine. To date, about 25 of these ELISA "positives" have been confirmed by mass spectrometry. We have also raised antibodies to phenylbutazone and furosemide to enable rapid and inexpensive quantitation of these permitted medications. Furosemide is a particular problem since its use requires a pre-race detention barn. For furosemide, we have developed a regulatory schedule based on our immunoassay test that allows elimination of the detention barn. For phenylbutazone, we have developed a similar immunoassay that allows rapid and inexpensive quantitation of this drug in blood. To enable racing authorities to test jockeys and other racetrack personnel, we have adapted PCFIA technology to human drug testing, and a full range of very sensitive tests for human drugs of abuse is available. These immunoassays are sufficiently sensitive to control abuse of the most potent drugs available to horsemen. In principle, an immunoassay can be raised to any drug within about six months, and made available worldwide at competitive rates. It appears clear that these non-isotopic immunoassays provide racing with the only technological basis that is sufficiently sensitive to detect the most potent abused drugs pre- and post-race, and has the flexibility to be readily adaptable to different drugs. Because of the high false negative rate generated by TLC, credible pre- and post-race testing programs cannot be based on TLC alone.(ABSTRACT TRUNCATED AT 400 WORDS)

Application of the Minnesota Code in evaluating electrocardiographic features of ischemic heart disease in patients exposed to carbon disulphide

We examined 81 men exposed for a long time to carbon disulphide (CS2) and tested the possible electrocardiographic (ECG) changes of ischemic heart disease (I.H.D.). The subjects were examined twice in two years. In order to make the ECG evaluation more objective, the Minnesota Code was applied. Two obligatory ECG examinations and only one submaximal effort test were carried out. For comparative evaluation, the control group was examined once. We proved that, in spite of the accepted opinion concerning the atheromatous action of CS2, this compound does not cause ECG symptoms of I.H.D. in a higher percentage of exposed persons. It also does not cause any significant increase in I.H.D. symptoms in dynamic ECG observations.

Application of a multistage classifier to the diagnosis of some occupational disease groups

This paper describes the basic concept of a multistage classifier and gives the results of the application of this approach to the diagnosis of vibratory syndrome and other diseases with similar symptoms. The multistage classifier was applied to classification of the most informative symptoms at particular stages of classification.