Room-temperature ultraviolet nanowire nanolasers

Room-temperature ultraviolet lasing in semiconductor nanowire arrays has been demonstrated. The self-organized, <0001> oriented zinc oxide nanowires grown on sapphire substrates were synthesized with a simple vapor transport and condensation process. These wide band-gap semiconductor nanowires form natural laser cavities with diameters varying from 20 to 150 nanometers and lengths up to 10 micrometers. Under optical excitation, surface-emitting lasing action was observed at 385 nanometers, with an emission linewidth less than 0.3 nanometer. The chemical flexibility and the one-dimensionality of the nanowires make them ideal miniaturized laser light sources. These short-wavelength nanolasers could have myriad applications, including optical computing, information storage, and microanalysis.

The Bohr effect of hemoglobin intermediates and the role of salt bridges in the tertiary/quaternary transitions

Understanding mechanisms in cooperative proteins requires the analysis of the intermediate ligation states. The release of hydrogen ions at the intermediate states of native and chemically modified hemoglobin, known as the Bohr effect, is an indicator of the protein tertiary/quaternary transitions, useful for testing models of cooperativity. The Bohr effects due to ligation of one subunit of a dimer and two subunits across the dimer interface are not additive. The reductions of the Bohr effect due to the chemical modification of a Bohr group of one and two alpha or beta subunits are additive. The Bohr effects of monoliganded chemically modified hemoglobins indicate the additivity of the effects of ligation and chemical modification with the possible exception of ligation and chemical modification of the alpha subunits. These observations suggest that ligation of a subunit brings about a tertiary structure change of hemoglobin in the T quaternary structure, which breaks some salt bridges, releases hydrogen ions, and is signaled across the dimer interface in such a way that ligation of a second subunit in the adjacent dimer promotes the switch from the T to the R quaternary structure. The rupture of the salt bridges per se does not drive the transition.

Target selection difficulty, negative priming, and aging

It has been recently suggested that the presence of identity negative priming effects in old adults could occur when there is substantial processing of the distracting information in a selective attention task (J. M. Kieley & A. A. Hartley, 1997). In three experiments, using a letter identification task, it was found that making target selection more difficult increased the magnitude of the negative priming effect to a similar extent in both young and old adults. Moreover, the size of the negative priming effect did not differ between young and elderly participants. These results are discussed with respect to the issue of age-related deficits in the mechanisms underlying negative priming.

The application of knowledge management principles to compliant coding activities

This article applies the concepts of knowledge management to diagnostic and procedural coding performed by health care providers. The process of diagnostic and procedural coding is both an art and a science. In particular, the information stored away in the minds of individuals performing the coding function is ripe for the basis of an effective knowledge Health Information Management (HIM) coding management system. In this article, we explore the issues and processes that HIM professionals can take advantage of in standardizing the coding function.

The role of diagnostic tests in therapeutic choices for gastroesophageal reflux disease

Gastroesophageal reflux disease has different clinical presentations that require different diagnostic and therapeutic approaches. This paper describes the appropriate use of diagnostic tests before and after treatment. Each diagnostic tool is examined from a practical point of view to determine the information it can provide and its possible pitfalls, and to comment on how it can influence therapeutic choices. Performing a preoperative diagnostic evaluation is especially stressed, so as not to select the wrong patient or the wrong procedure. Finally, failures of surgery are examined to understand their causes and to prevent them. The value of the most relevant examinations for diagnosing the causes of failures and choosing the appropriate solution are discussed.

Neurophysiologic exploration: a reliable tool in HIV-1 encephalopathy diagnosis in children

BACKGROUND

HIV-1 related encephalopathy has a bad prognostic meaning in the course of AIDS disease, but the early association of different drugs can modify its course. For this reason it is very important to recognize CNS involvement as soon as possible. As shown in the literature, at least in adult studies, EEG and Evoked Potentials (EP) are good tools in evaluating CNS alterations. In children data are rare.

METHODS

A ten-year prospective study of 44 infected children out of 142 born from HIV-1 positive mothers has been done. The children have been submitted to EEG recording every six months in the first 18 months of life and then every year, to multimodal EP every six months. A total of 357 EEG, 47 P-VEP, 62 F-VEP and 98 BAEP have been performed.

RESULTS

EEG: we found no pathologic results in patients belonging to category A; results were pathologic in 17.7% in category B, in 47.7% in C and in 77% of encephalopathic patients. It seems that EEG alterations are parallel to disease progression, with a relative risk of developing encephalopathy (R.R. = 1.15) and of death (R.R. = 2.33) for patients belonging to category C. We obtained a statistically significant lengthening in BAEP interpeak latency of left ear in all groups. For patients in category C the risk of developing encephalopathy is statistically significant (p = 0.045; R.R. = 6.75) and risk of death is high (R.R. = 4).

CONCLUSIONS

Neurophysiologic exams are a reliable tool for the diagnosis of encephalopathy, in addition to clinical evidence.

Long-term oxygen therapy

The role of long-term oxygen therapy in the management of patients with hypoxemia is discussed. A brief history of the use of long-term oxygen therapy and its benefits is provided. The actual prescription of long-term oxygen therapy and reimbursement issues are reviewed. The use of long-term oxygen therapy, particularly in the home and for travel is addressed. In recent times, the focus of oxygen therapy delivery has shifted to allow patients receiving repeated oxygen therapy to have increased mobility. Lighter and more portable equipment is now used, and oxygen-conserving devices have been developed that allow the patient's oxygen supply to last longer. An update on this equipment and these devices is provided.

TT virus infection in haemodialysis patients

BACKGROUND

The recent discovery of a new parenterally transmitted DNA virus called TT virus (TTV) led us to investigate its prevalence in haemodialysis patients, a high-risk group for blood-borne infection, and to evaluate its role in liver disease. Moreover, we compared the TTV prevalence with the prevalence of other hepatitis virus coinfections.

METHODS

Serum samples of 78 patients on maintenance haemodialysis were tested for TTV-DNA, hepatitis G virus (HGV)-RNA, anti-E2, anti-hepatitis C virus (HCV) and HCV-RNA. TTV-DNA was detected by semi-nested PCR using the primers from open reading frame 1 (ORF). HGV-RNA was detected by PCR using specific primers for the NS3 and the 5'-UTR genome regions while anti-E2 were checked by an enzyme immunological test. Anti-HCV was tested by the second generation Chiron RIBA HCV test system. HCV-RNA was evaluated by nested PCR with primers directed to the highly conserved 5' non-coding region of the HCV genome.

RESULTS

TTV prevalence in our patients was 19% (15/78) while the prevalence of HCV and HGV infection proved to be 20 and 15.4%, respectively. Among TTV positive patients HGV co-infection was present in five cases (33%), HCV in six cases (39.9%), while HBV co-infection was not present in any of the patients. Only three patients proved positive for all three viruses. ALT levels were normal in most cases (13/15; 86%). In particular, patients with TTV infection alone showed normal ALT levels and HCV coinfection was found in the two patients with moderate ALT increases.

CONCLUSIONS

TTV prevalence in haemodialysed patients is significant though the real clinical impact is still unclear. However, we must keep in mind that the epidemiological relevance of TTV infection is probably underestimated due to the impossibility in detecting the corresponding antibody.

How long is enough? Defining the treatment length in endovascular brachytherapy

The International Commission on Radiation Units and Measurement (IRCU) 50 has clearly defined treatment volumes in radiation therapy in the management of neoplasms. These concepts are applied to the field of endovascular brachytherapy (EVBT) for the prevention of postangioplasty restenosis. The following definitions are proposed: gross target length (GTL) is defined as the narrowed segment of the artery that requires intervention. Clinical target length (CTL) is defined as the intervened or injured length, which could be due to angioplasty, stent strut injury, stent deployment, or debulking procedures. Planning target length (PTL) is the CTL plus a margin to account for heart/catheter movement and uncertainty in target localization. The final treatment length (TL) is the PTL plus the effect of penumbra. The accurate specification of treatment length serves several important purposes. Based on an understanding of the different factors constituting the treatment length, adequate margins can be provided beyond the GTL; this will avoid geographic misses and minimize edge failures. These definitions of target length ensure treatment consistency and provide a standard terminology for communication among practitioners of EVBT, something of critical importance in the conduct of multi-institutional trials in this new and multidisciplinary therapy. Finally, since the efficacy of EVBT is critically dependent on the precision of radiation delivery, these guidelines ensure that the benefits of EVBT seen in prospective randomized trials can be translated into daily clinical practice at the community level.

Augmenting local bone with Grafton demineralized bone matrix for posterolateral lumbar spine fusion: avoiding second site autologous bone harvest

Mineralization and integrity of the bone graft mass were evaluated among patients having posterolateral fusion. Grafting consisted of a composite of Grafton and "local" autologous bone (n=56) or iliac crest autograft alone (n=52). Mineralization was rated radiographically at baseline and at 3, 6, 12, and 24 months. Integrity was judged as fused or not fused. Mineralization ratings did not differ significantly between groups at any postoperative interval (P values of .25-1.00). The percentage of patients fused was similar in both groups (60% and 56% for Grafton and controls, respectively; P=.83). Fifteen control patients reported donor site pain. These findings warrant further evaluation of this composite.

Target selection difficulty, negative priming, and aging

It has been recently suggested that the presence of identity negative priming effects in old adults could occur when there is substantial processing of the distracting information in a selective attention task (J. M. Kieley & A. A. Hartley, 1997). In three experiments, using a letter identification task, it was found that making target selection more difficult increased the magnitude of the negative priming effect to a similar extent in both young and old adults. Moreover, the size of the negative priming effect did not differ between young and elderly participants. These results are discussed with respect to the issue of age-related deficits in the mechanisms underlying negative priming.

Acute non A-E hepatitis in eastern Sicily: the natural history and the role of hepatitis G virus

BACKGROUND

The etiology and the natural history of acute non A-E hepatitis is still undefined.

METHODS

We examined the prevalence of HGV viraemia and the long-term outcome in 54 patients with non A-E acute hepatitis.

RESULTS

HGV-RNA was found in 19 out of 54 (35%) patients. There was no difference between HGV-RNA positives and negatives in terms of age sex, parenteral risk factors and alanine amino-transferase peak level. Gamma-glutamyl transpeptidase levels were higher in the HGV-RNA positive group. During a 3-year follow up, 10 out of 54 (18.5%) patients progressed to chronic hepatitis and 4 out of 10 (40%) had an histologically advanced disease. None of the 19 subjects infected with HGV showed a chronic evolution of liver disease.

CONCLUSIONS

Our results confirm the limited role of HGV as the etiological agent of non A-E acute hepatitis. The great majority of non A-E hepatitis cases are yet of undetermined origin and unfortunately, are characterized by a high rate of progression to chronic active hepatitis.

Anaesthesia with desflurane-nitrous oxide in elderly patients. Comparison with isoflurane-nitrous oxide

BACKGROUND

Desflurane is a new volatile anaesthetic, very little soluble. We wished to compare efficacy, safety, and emergence and recovers; profiles of desflurane-N2O versus isoflurane-N2O anaesthesia in elderly patients.

METHODS

EXPERIMENTAL DESIGN

single blind, prospective randomised study.

SETTING

operating rooms of two major teaching hospitals affiliated with the University of Milan.

PATIENTS

fifty-seven patients ASA physical status II or III, aged 65 or older, undergoing urological (non-endoscopic), orthopaedic or gynaecological (non-laparoscopic) surgery of at least one hour duration, were randomly assigned to receive general anaesthesia with either desflurane or isoflurane in 60% N2O- 40% O2, after standardised premedication and induction.

MEASUREMENTS

vital signs, end-tidal agent, narcotic requirement, and adverse event appearance were monitored throughout the study.

RESULTS

Twenty-eight patients received desflurane and 29 isoflurane. Demographics, anaesthesia duration and exposure, and intraoperative fentanyl requirement were comparable in the two groups. Immediate emergence from anaesthesia (time to extubation and hand grip on command) was faster in desflurane group, albeit not significantly (8.4 +/- 6.4 vs 11.0 +/- 6.5 min and 8.6 +/- 6.0 vs 11.8 +/- 6.0); on the contrary, early recovery (time to state the name and date of birth) was significantly shorter in patients receiving desflurane (11.1 +/- 6.2 vs 17.3 +/- 7.8 min and 13.1 +/- 6.0 vs 20.9 +/- 10.9 min). Only 24 patients (12 in desflurane and 12 in isoflurane group) did need postoperative fentanyl administration; among them, requirement was significantly higher in desflurane patients (3.4 +/- 1.1 vs 2.4 +/- 1.3 micrograms.kg-1. Total time in recovery room was not different between anaesthetics, as well as adverse event prevalence and severity.

CONCLUSIONS

Early recovery in elderly patients is faster after desflurane than isoflurane anaesthesia; this might contribute to increased requirement of postoperative analgesia. Occurrence of adverse event is comparable between the two anaesthetics.

Hepatitis G virus infection in haemodialysis and in peritoneal dialysis patients

The aim of this study was to detect hepatitis G virus RNA (HGV RNA) and antibodies against the virus envelope protein E2 (anti-E2) in 107 patients either on maintenance haemodialysis (n = 78) or peritoneal dialysis (n = 29) to evaluate the prevalence of HGV infection and to establish its role in liver disease. The total prevalence of HGV infection was of 15.4% among haemodialysis patients, whereas it was 10.3% among peritoneal dialysis patients. HGV RNA was detected in 2 haemodialysis patients (2.6%) and in 3 peritoneal dialysis patients (10.3%). Anti-E2 was found in 10 haemodialysis patients (7.8%), whilst all peritoneal dialysis patients resulted negative. In only 1 patient the alanine aminotransferase level was elevated. This patient underwent liver biopsy that did not reveal evidence of chronic hepatitis. The lower HGV prevalence in haemodialysis patients, when compared with data reported by other European authors, should be related to the lower rate of polytransfused patients in our series (29.5%). Multiple blood transfusions should be considered as the main factor to explain the different prevalence of HGV infection among various European dialysis centres. Detection of both antibody and viraemia is important to establish the real rate of the infection.

Favourable outcome in 135 children with juvenile systemic sclerosis: results of a multi-national survey

OBJECTIVE

To increase the current knowledge of the outcome of juvenile systemic sclerosis (jSSc), which is currently limited.

METHODS

In order to investigate the patient outcome and prognostic factors, starting October 1994, we distributed questionnaires to 324 paediatric rheumatology centres.

RESULTS

Until 15 May 1998 responses from 46 centres were received, 34 of which returned completed questionnaires on a total of 135 patients. One hundred and twenty-two of the 135 patients were Caucasian, 100 were female. The mean age at disease onset was 8.8 yr (S.D. +/- 3.3 yr). The mean disease duration at the last follow-up was 5 yr(S.D. +/- 3.3 yr). At the last follow-up the disease was still active and required medication in 82 patients, 36 had inactive disease on medication, and 16 were in remission. Ninety per cent of the living patients were fully active in daily life at the last follow-up. Eight of the 135 patients had died. These patients had a median age at onset of the disease of 10.5 yr (range 6.7-15.8 yr). The median disease duration until death was 2 yr (range 1-8 yr). The causes of death were heart failure (five), renal failure (one), sepsis (one) and in one case the cause was not defined. The 1 yr survival rate was 99%, the 2 yr was 97% and the 4 yr was 95%.

CONCLUSIONS

At a mean follow-up of 5 yr, the current results show a favourable outcome in most patients with childhood onset jSSc and a significantly better survival than in the adult SSc patients.

Laparoscopic colectomy: indications, standardized technique and results after 6 years experience

BACKGROUND/AIMS

The aim of the present study was to perform a retrospective study of our experience in performing laparoscopic colon surgery after 6 years experience.

METHODOLOGY

From April 1992 to April 1998, 215 patients underwent colon laparoscopic surgery. There were 121 females and 94 males, whose average age was 66.7 (range: 31-92).

RESULTS

170 laparoscopic procedures were completed out of 215 (79%): 151 resections (22 for a benign lesion and 129 for a malignant one), 4 reversal of Hartmann's procedures, 6 rectopexy, 3 ileotransverstomies and 6 suture of traumatic colon perforation. There were 3 mortalities out of 215 (1.9%). The conversions were 45 out of 215 (20.9%); 22 (10.2%) cases were, however, converted to a laparoscopic facilitated procedure. The most common causes for conversion were the presence of bulky tumors and/or tumors that contaminated the adjacent structures (16/215), adhesions due to previous operations (9/215) and the patient's obesity (8/215). There were 39 complications (18.1%), 10 (4.6%) out of which required reoperation (2 anastomotic fistula, 2 anastomotic leak, 2 anastomotic stenosis, 2 hemorrhage, 1 colic iatrogenic perforation and 1 occlusion to rotation of anastomosis). There were only 2 recurrences (1.3%), 15 months (C2) and 8 months (B2) after the operation for intraoperative technical error. The average number of lymph nodes harvested in resected specimens was 12.8 (range: 1-41), whereas the mean distance of the tumor from the proximal margin of resection was 11.5 cm (range: 5-35), and from the distal margin 7.5 cm (range: 1-25). The average operative time was 165 min (range: 40-360), and the mean hospital stay was 9.2 days (range: 6-40).

CONCLUSIONS

A colon resection for a malignant lesion, if performed with the highest respect for the oncologic principles, proves that it is impossible to develop a wall and intraluminal recurrence, which, in our opinion, may be caused by an improper surgical technique. Therefore, neoplastic colon laparoscopic surgery must be the perogative of a few selected and specialized centers.

Defective suppression of the aldosterone biosynthesis during stroke permissive diet in the stroke-prone phenotype of the spontaneously hypertensive rat

Previous studies have shown that short-term high salt intake unmasks blunted plasma aldosterone suppression in stroke-prone spontaneously hypertensive rats (SHRsp). The aim of this study was to evaluate the response of aldosterone biosynthesis and production to a sustained exposure to the stroke-permissive Japanese-style diet (JD) in young stroke-prone and stroke-resistant SHRs. For this purpose, 6-week old male rats from both strains were divided into 2 dietary groups and received regular diet (SHR = 37, SHRsp = 32) or the JD and 1% saline to drink (SHR = 34, SHRsp = 30) for 4 weeks. All measurements were carried out at the end of the dietary periods. After JD, plasma aldosterone levels were significantly decreased in SHR (from 357.8 +/- 57 to 163.3 +/- 31.5 pg/ml, p < 0.05) but markedly increased in SHRsp (from 442 +/- 56.5 to 739 +/- 125.7 pg/ml, p < 0.05). Consistently, the adrenal aldosterone synthase expression was reduced by JD in SHR (p < 0.05), whereas it was even slightly raised by JD in SHRsp so that, at the end of JD, aldosterone synthase mRNA was 5-fold higher in SHRsp than in SHR. Urinary sodium excretion (mEq/24h) achieved lower levels in SHRsp, so that fractional excretion of sodium was 80.2 +/- 9% in SHR and 40.3 +/- 8% in SHRsp (p < 0.05) in balance studies performed at the end of JD. These different responses of mineralocorticoid biosynthesis and urinary sodium excretion to JD were not accounted for by different adaptations of the renin-angiotensin and atrial natriuretic peptide systems, of serum potassium levels, or of adrenal 11beta-hydroxylase expression in the two strains. Systolic blood pressure was comparable in both strains throughout the experiment. These results demonstrate enhanced aldosterone biosynthesis, associated with reduced urinary excretion of sodium in response to JD in SHRsp before the onset of stroke. This abnormality may play a role in the higher susceptibility to stroke of this model.

Implementation of advance directives among community-dwelling veterans

To evaluate the feasibility and effectiveness of implementing a "Let Me Decide" advance directive education program among veterans living in the community, the authors studied 150 veterans in south central Ontario. Thirty-four veterans had preexisting Powers of Attorney and were removed from the analysis, leaving a total sample of 116. Two methods of systematically implementing a directive program were evaluated after the intervention period and 6 months later. Eighty-two (71%) of the 116 veterans expressed interest in receiving detailed information about the program, and 67 (82%) of the 82 interested veterans were educated. Forty-two (63%) of the 67 educated veterans completed directives. Of the 116 interested veterans, 42 (36%) completed directives. Veterans who were educated about directives were surveyed at follow-up, and 37 of 38 (97%) respondents reported that the education process was beneficial and should be offered to other veterans. This response pattern was consistent among those who completed and those who did not complete directives.

Systematic implementation of an advance directive program in nursing homes: a randomized controlled trial

CONTEXT

Although advance directives are commonly used in the community, little is known about the effects of their systematic implementation.

OBJECTIVES

To examine the effect of systematically implementing an advance directive in nursing homes on patient and family satisfaction with involvement in decision making and on health care costs.

DESIGN

Randomized controlled trial conducted June 1, 1994, to August 31, 1998.

SETTING AND PARTICIPANTS

A total of 1292 residents in 6 Ontario nursing homes with more than 100 residents each.

INTERVENTION

The Let Me Decide advance directive program included educating staff in local hospitals and nursing homes, residents, and families about advance directives and offering competent residents or next-of-kin of mentally incompetent residents an advance directive that provided a range of health care choices for life-threatening illness, cardiac arrest, and nutrition. The 6 nursing homes were pair-matched on key characteristics, and 1 home per pair was randomized to take part in the program. Control nursing homes continued with prior policies concerning advance directives.

MAIN OUTCOME MEASURES

Residents' and families' satisfaction with health care and health care services utilization over 18 months, compared between intervention and control nursing homes.

RESULTS

Of 527 participating residents in intervention nursing homes, 49% of competent residents and 78% of families of incompetent residents completed advance directives. Satisfaction was not significantly different in intervention and control nursing homes. The mean difference (scale, 1-7) between intervention and control homes was -0.16 (95 % confidence interval [CI], -0.41 to 0.10) for competent residents and 0.07 (95% CI, -0.08 to 0.23) for families of incompetent residents. Intervention nursing homes reported fewer hospitalizations per resident (mean, 0.27 vs 0.48; P = .001) and less resource use (average total cost per patient, Can $3490 vs Can $5239; P = .01) than control nursing homes. Proportion of deaths in intervention (24%) and control (28%) nursing homes were similar (P = .20).

CONCLUSION

Our data suggest that systematic implementation of a program to increase use of advance directives reduces health care services utilization without affecting satisfaction or mortality.

Analysis of the genetic basis of the endothelium-dependent impaired vasorelaxation in the stroke-prone spontaneously hypertensive rat: a candidate gene approach

OBJECTIVE

To investigate the role of potential candidate genes in the pathogenesis of the endothelium-dependent impaired vasorelaxation that associates and co-segregates with stroke in the stroke-prone spontaneously hypertensive rat (SHRsp) compared with the stroke-resistant SHR (SHRsr).

DESIGN AND METHODS

An SHRsp/SHRsr F2-intercross (n = 137; 64 males, 73 females) was obtained and, at the age of 6 weeks, it was placed under a stroke permissive Japanese-style diet for 4 weeks. At the end of the treatment the vascular function of each rat was characterized. The maximal vasorelaxation to acetylcholine after maximal vasoconstriction (delta ratio) was considered as the quantitative phenotype. The following candidate genes were related to the delta ratio: renin, angiotensinogen, angiotensin-converting enzyme, angiotensin II AT1b receptor, atrial natriuretic peptide, brain natriuretic peptide, atrial natriuretic peptide GC-A receptor, kallikrein, endothelial nitric oxide synthase. In addition, polymorphic markers located inside areas of the rat genome where other candidates (i.e. adrenomedullin, endothelin, Ang II AT1a receptor) are known to map were included.

RESULTS

The endothelial vascular dysfunction of the SHRsp showed a variable distribution among SHRsp/SHRsr F2 descendants, independently from the blood pressure levels. A genotype/phenotype co-segregation analysis for each of the genes tested did not show any statistically significant co-segregation with the vascular phenotype.

CONCLUSION

A candidate gene approach used to investigate the genetic basis of the endothelial-dependent vascular dysfunction of the SHRsp strain did not reveal any evidence to support the hypothesis that the genes tested play any role in the pathogenesis of the stroke-related vascular abnormality.

Nephrotic syndrome and plasmapheresis

We studied 15 patients suffering from nephrotic syndrome (NS) in bioptically-accertained primary and secondary glomerulopathies responding poorly to the common pharmacological treatment. They were monitored for one year by assessing their immunological and kidney functionality parameters, especially proteinuria. The patients underwent 3 apheretic sittings using the cascade double-filtration technique. After the third apheretic sitting the patients received metilprednisolone 300 mg/m2. This therapy was repeated every month for 6 months. At the end of the apheretic cycle it was shown that all patients had responded well to the therapy with a dramatic decrease in proteinuria, maintenance and/or recuperation of kidney functionality and improvement of lipidic asset; these data remained unchanged over time. Considering our preliminary results, we believe that therapeutic apheresis has a precise function in refractory nephrotic syndrome and, in particular, we propose the use of the cascade double-filtration technique.