Effects of low- and high-flux dialyzers on oxidative stress and insulin resistance

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of mortality in patients with end-stage renal disease (ESRD). The cornerstone of high CVD incidence in ESRD patients is endothelial dysfunction which results from inflammation, oxidative stress and insulin resistance. Although various modalities of hemodialysis (HD) have been presumed to exert different effects on oxidative stress and insulin resistance, solid evidence is still lacking.

METHODS

40 ESRD patients undergoing HD were prospectively enrolled and divided randomly into two groups. Patients in each group received either F8 HPS (low-flux) (Group A) or FX80 (high-flux) (Group B) as HD dialyzers for 2 consecutive months. Diet pattern and medications were kept as usual in both groups to avoid considerable blood glucose change during study period. Blood samples were taken at the start and end of the study.

RESULTS

A total of 38 patients (18 and 20 for Groups A and B, respectively) completed the study. Within each group, there was no change in adiponectin, plasma 8-iso-prostaglandin F(2)(alpha), high-sensitivity C-reactive protein, blood glucose and insulin after 2 months of treatment except a significant change of HOMA(IR) (p = 0.02) in high-flux group. The significant change of HOMA(IR) between the two groups (p = 0.017) mainly results from the parallel change of insulin between the two groups (p = 0.03).

CONCLUSION

For patients receiving HD, the high-flux dialyzer with synthetic polysulfone membranes fails to provide a better anti-inflammatory or antioxidative effect than the low-flux dialyzer; however, the high-flux dialyzer does significantly improve insulin resistance in this short-term study. This result implies that the high-flux dialyzer might provide better cardiovascular protection than the low-flux dialyzer. Therefore, the low-flux dialyzer might be considered for patients who only need short-term HD therapy. Regarding patients under long-term maintenance HD therapy, a high-flux dialyzer might be the choice of dialyzer.

Applying a multiple screening program aided by a guideline-driven computerized decision support system - a pilot experience in Yun-Lin, Taiwan

BACKGROUND/PURPOSE

Although preventive tools decrease morbidity and mortality and promote health, these services are often underutilized. The purpose of this study was to create a workflow for an outpatient setting that incorporated a computerized decision support system to implement preventive recommendations as well as to evaluate its impacts on facilitating preventive care.

METHODS

Subjects visiting National Taiwan University Hospital Yun-Lin Branch were evaluated by a questionnaire, which contained items to trigger production rules to check the eligibility of screening for high coronary risk, diabetes mellitus, lipid disorder, hypertension, obesity, tobacco use, depression, colorectal cancer, breast cancer, cervical cancer, and osteoporosis. Patients were given health information about the diseases they were at risk for and the merits of preventive measures, scheduled for a clinic visit, and arranged to have access to screening tools. Physicians were prompted with clinical reminders on the encounter. The over-all effectiveness of 11 components in this screening program was evaluated in terms of expected life saving. The cost-effectiveness ratio was represented in US dollars per life-year saved.

RESULTS

A total of 283 men and 199 women were identified to need one to six preventive interventions during a 2-month period. Preventive consultation was arranged and screening tools were performed. It was estimated that 412-1014 subjects would be needed to attend the program so as to save one life. The cost-effectiveness ratio ranged from 30,000 US dollars to 40,000 US dollars per life-year saved.

CONCLUSION

A computer-aided screening program driven by the US Preventive Services Task Force recommendations has been successfully implemented in Yun-Lin, Taiwan, and provided useful information about local epidemiology and implications for future health policy making.

Potential Ototoxicity of Aluminum in Hemodialysis Patients

OBJECTIVES/HYPOTHESIS

Aluminum (Al) is a neurotoxin in both human and animal models. Al accumulation is usually observed in patients with end-stage renal disease (ESRD). To clarify whether Al also exhibits toxic effects on the specified neural organ of inner ear, we recruited hemodialysis (HD) patients to investigate the effect of serum Al level on the auditory physiology.

STUDY DESIGN

Forty patients in maintenance HD as well as 40 age-matched healthy subjects without hearing complaints were enrolled. The auditory function tests, including pure-tone audiometry (PTA), distortion-product otoacoustic emissions (DPOAEs), and auditory brainstem response (ABR) were performed in all subjects. The serum Al levels determined within 3 months of auditory tests were used for analysis.

RESULTS

High-frequency hearing impairment was the predominant auditory dysfunction in HD patients who showed worse high-tone hearing level on PTA and diminished amplitudes of DPOAEs at 3 K and 4 K as compared with the controls (P < .001). Age was a significant factor determining the auditory dysfunction in both HD patients and control subjects. After age correction, serum Al level correlated reversely with the amplitude of DPOAEs-2 K (P = .002), but not with amplitudes of DPOAEs-3 K, -4 K, hearing levels on PTA, or wave latencies on ABR.

CONCLUSION

High-frequency hearing impairment is a common presentation in HD patients. Serum Al level correlates reversely with the amplitude of DPOAEs-2 K but not those of DPOAEs-3 K, -4 K, hearing levels on PTA, and wave latencies on ABR. Possibly, the correlation between the Al level and the high-frequency OAE results was obscured by the significantly diminished amplitudes of DPOAEs-3 K, -4 K in ESRD patients. These results implicate that the effect of Al is mainly of cochlear origin rather than of retrocochlear origin.

Clinical characteristics of patients with segmental renal infarction

BACKGROUND

Renal infarction is usually an underestimated disease due to its rare and non-specific presentations; the renal survival of these patients is not well studied. The aim of the present analysis is to study the clinical features and outcome in patients who had documented renal infarction.

METHODS

Twenty-two patients (12 men and 10 women, mean age of 57.7 +/- 3.44 years (28.4-83.3 years)) with image-confirmed segmental renal infarction in the past 15 years were enrolled. All patients were followed up at outpatient department with a median of 4 years (1-14 years). Initial and follow-up clinical characteristics and laboratory results were recorded.

RESULTS

The most common underlying disease was cardiovascular disease. Renal infarction often presented with non-specific symptoms, including flank pain (55%), vague abdominal pain (50%), nausea/vomiting (46%) and fever (27%). The levels of leucocytes, lactate dehydrogenase, blood urea nitrogen and serum creatinine were all elevated at admission. The early diagnosis group (12/22) had more obvious flank pain, nausea/vomiting (P < 0.001) and higher alanine transaminase (P = 0.02). It also predisposed to undergo antiplatelet or anticoagulant therapy (all P < 0.04). During follow up, there was no recurrence in the whole study group, and a trend of better recovery of renal function was noted in the early diagnosis group.

CONCLUSION

The serum creatinine level correlates with longer hospitalization length (P < 0.05). As regards long-term prognosis, no definite factor or treatment was found to have significant effect in segmental renal infarction patients. However, early diagnosis and early initiation of treatment seems to have a positive effect on future renal outcome.

Neuroleptic Malignant Syndrome After the Use of Venlafaxine in a Patient with Generalized Anxiety Disorder

Neuroleptic malignant syndrome (NMS) is a potentially lethal adverse reaction to neuroleptics, which is characterized by hyperthermia, extrapyramidal symptoms, altered consciousness and autonomic dysfunction. Although NMS is most commonly induced by the high-potency neuroleptics, its development has also been associated with the use of non-neuroleptic agents that block central dopamine pathways. A 68-year-old man with generalized anxiety disorder and depressive symptoms presented at the emergency department (ED) with high fever, tremor, muscle rigidity, rhabdomyolysis and altered mental status. NMS was considered to have been caused by the recent addition and subsequent dose increase in his treatment regimen of venlafaxine, a serotonin norepinephrine reuptake inhibitor. He was successfully treated with bromocriptine, lorazepam, and fluid hydration in the ED and intensive care unit.

Factors associated with increased plasma homocysteine in patients using an amino acid peritoneal dialysis fluid

BACKGROUND

Although amino acid peritoneal dialysate (AAPD) substitution is thought to improve protein-energy malnutrition in patients undergoing peritoneal dialysis (PD), it may also increase plasma homocysteine (Hcy) levels due to the methionine load in the dialysate. However, it is still unclear which factors are important for elevating Hcy in patients treated with AAPD.

METHODS

Sixteen malnourished PD patients (age 48+/-18 years) were treated daily with one exchange of 1.1% AAPD for 3 months. The effects of AAPD on nutrition, Hcy, methionine, leptin and insulin resistance were studied. We also analysed factors that influenced plasma Hcy levels.

RESULTS

We found a transient increase in serum albumin (P<0.01) after 1 month treatment, especially in patients with serum albumin < or = 3.5 g/dl. Total plasma Hcy increased markedly after AAPD (the peak at month 2, P<0.001) and returned to baseline after ceasing AAPD, despite no changes in dietary methionine intake and serum methionine levels. Eight patients with Hcy increments >5.65 microM (the median) had lesser dietary intakes of protein (P = 0.01) and methionine (P = 0.028), lower body fat mass (P = 0.05) and lower aspartate transaminase (AST) (P = 0.008) before AAPD treatment than patients with lower increments. DeltaHcy was inversely correlated with baseline dietary methionine intake (r = -0.61), protein intake (r = -0.54) and AST (r = -0.51) (all P<0.05). There was no change in leptin or insulin resistance. AAPD treatment significantly increased Kt/Vurea (P<0.001), weekly creatinine clearance (P<0.05) and peritoneal glucose transport (P<0.05).

CONCLUSIONS

Treatment with 1.1% AAPD transiently increased serum albumin in malnourished PD patients. However, the methionine load from the dialysate in this study significantly elevated plasma Hcy levels, especially in patients with lower protein and methionine intakes, and lower AST levels. Further long-term studies will be needed to clarify potential nutritional benefits and adverse effects of AAPD.

Effect of highly active antiretroviral therapy on diagnoses of sexually transmitted diseases in people with AIDS

BACKGROUND

There has been an increase in high-risk sexual behaviour and sexually transmitted diseases (STD) during the time period when highly active antiretroviral therapy (HAART) became widely available. We examined whether taking HAART increased the risk of acquiring an STD--an epidemiological marker of unsafe sex--in people with AIDS.

METHODS

We did a computerised match of people in the San Francisco STD and AIDS registries. People with AIDS who were diagnosed before 1999 and alive in November, 1995, or later, were classified as having had an STD after AIDS diagnosis or not having had an STD after AIDS diagnosis. We used a Cox proportional hazards model to see whether use of antiretroviral therapy was associated with acquiring an STD after AIDS, after adjustment for sex, age, race, HIV-1 risk category, and CD4 count at AIDS diagnosis.

FINDINGS

People with AIDS who had had HAART showed an independent increase in the risk of developing an STD (hazard ratio 4.10; 95% CI 2.84-5.94). Americans of African origin, younger age, and higher CD4 count at AIDS diagnosis were also associated with acquiring an STD after AIDS. The number of people living with AIDS who acquired an STD increased over time from 60 (0.66%) in 1995 to 113 (1.32%) in 1998 (p<0.001).

INTERPRETATION

We have shown that people on HAART are more likely to develop an STD, an epidemiological marker of unsafe sex. More intensive risk-reduction counselling and STD screening for people with AIDS is needed.

Soliton wavelength-division multiplexing system with channel-isolating notch filters

We propose a wavelength-division multiplexing system in which transmission of solitons is stabilized by fixed- or sliding-frequency notch filters (a soliton rail), providing channel isolation. We demonstrate analytically and numerically that a soliton trapped in a channel between two notches is very robust. We also predict an optimum ratio between the channel separation and the soliton's spectral width. The effects of interchannel collisions are considered, and it is demonstrated that these effects can be largely eliminated by notch filters, which require a compensatory gain that is comparable with the basic gain balancing the fiber loss.

Linking clients from HIV antibody counseling and testing to prevention services

The effectiveness of HIV antibody counseling and testing as a prevention intervention is limited: persons testing seronegative do not usually change their risk behaviors, some actually increase their risk behaviors, and decreases in risk behaviors are usually short-lived. Referrals to additional prevention and other needed services are therefore recommended, although the extent and determinants of referral provision for persons testing seronegative are unknown. We assessed the prevalence of referrals and the association between risk behaviors and prevention referrals among seronegatives. We reviewed HIV testing and referral data on all persons receiving confidential seronegative test results in San Francisco (SF) in the first 10 months of 1995 (n = 5,595), and gathered more detailed referral information at the municipal STD clinic from November 1995 through May 1996 (n = 747). The overall prevalence of referrals was low: a referral was given to 19.1% of the SF sample and 10.6% of the STD clinic sample; 15.4% of the SF sample and 5.9% of the STD clinic sample received a prevention referral. Injection drug users (IDUs) were the most likely to receive a prevention referral (48.5% of SF IDUs, 36.4% of STD clinic IDUs); men having sex with men and women with high-risk partners were also more likely to get a prevention referral than others. For SF IDUs, unsafe sex and needle sharing were not associated with an increased likelihood of receiving a prevention referral. Opportunities to link high-risk clients from counseling and testing to HIV prevention services are being missed. The referral component of HIV counseling and testing should be improved.

Breathing spatial solitons in non-Kerr media

The concept of soliton internal mode is introduced to explain quantitatively the long-lived oscillations of self-guided beams, or breathing spatial solitons. Cubic-quintic nonlinearity is considered in detail, and it is shown that the existence of the internal mode affects strongly the beam propagation in non-Kerr media, leading to oscillatory dependence of the output width of the beam versus its input power.

Suppression of self-pulsing in an erbium-doped fiber laser

We propose a scheme whereby the self-pulsation that commonly occurs in an erbium-doped fiber laser can be suppressed. The scheme consists of the addition of a low-power laser as an auxiliary pump. The required auxiliary pump power is only a few percent of the output lasing power. There is reasonable agreement between experimental and theoretical results.

Nonlinear-optical amplifier based on a dual-core fiber

We propose a scheme for all-optical amplification based on a nonlinear-optical coupler in which one core is amplifying while another is attenuating. In this scheme the input signal is fed into the amplifying core, from where the output is also obtained. A weak input easily couples to the lossy core and gets dissipated in it, whereas a stronger signal stays and undergoes a nearly linear amplification in the active core. When it is used for reshaping pulses in a long transmission line, this scheme should allow the pulses to be amplified while simultaneously suppressing the noises between them. Simulating equations for the cw signal in this model, we are able to find a regime that provides for a strong contrast between the suppression of weak signals and amplification of strong ones as well as a steep transition from suppression to amplification at a certainthreshold.

Use of antidiabetic and antihypertensive drugs in hospital and outpatient settings in Hong Kong

OBJECTIVE

To investigate the usage patterns of antidiabetic and antihypertensive drugs and to identify any discordance between recommended management guidelines and clinical practice in two study locations.

DESIGN

Prescription survey.

SETTING

A government- operated general outpatient clinic (GOPC) and a medical/geriatric specialist clinic (SC) affiliated with a regional hospital in the same district.

PATIENTS

Patients presenting with a prescription during the study period at the respective pharmacy were classified as having diabetes if at least one antidiabetic agent was prescribed and as having hypertension if a cardiovascular drug was prescribed in a hypotensive dosage.

MAIN OUTCOME MEASURE

The pattern of use of antidiabetic and antihypertensive drugs.

RESULTS

One thousand one hundred forty-four consecutive prescriptions were collected in the GOPC, and 1523 in the SC. Of 9.4% (n = 107) of patients were classified as having diabetes in the GOPC and 20.4% (n = 310) in the SC (p<0.001). Most patients with diabetes were taking oral hypoglycemic agents (98.1% in GOPC vs. 84.5% in SC). Glibenclamide was the sufonylurea used most often as monotherapy in both settings (50.5% in GOPC vs. 40.6% in SC). The combined use of a sulfonylurea with metformin was common in both settings (22.4% in GOPC vs. 28.4% in SC). Metformin monotherapy (1.9% in GOPC vs. 2.6% in SC) and combination treatment of insulin with an oral agent (0% in GOPC vs. 2.6% in SC) were rarely prescribed. In the GOPC, 24.5% (n = 280) of patients were prescribed an antihypertensive drug compared with 47.1% (n = 717) in the SC (p< 0.001). In the GOPC, the use of antihypertensive drugs was more prevalent in those with diabetes (53.5%) than in the remaining patients without diabetes (21.5%, p<0.001). In the SC, 51% of patients with diabetes were receiving antihypertensive drugs, but 40% of patients without diabetes were also receiving three treatments. In the GOPC, diuretics (indapamide 14.3% other 59%) and methyldopa (9.5%) were the most frequent choices of antihypertensive drugs when used as monotherapy in subjects without diabetes. In the SC, apart from diuretics (indapamide 12.9%, other 20.3%), beta-blockers (29%) also were prescribed frequently. If treated with only one antihypertensive drug, most patients with diabetes in the GOPC were prescribed indapamide (72.7%), and patients in the SC were treated mainly with angiotensin-converting enzyme inhibitors (35%) indapamide (22.5%), or calcium-channel blockers (13.8%).

CONCLUSIONS

In this prescription-based survey, diabetes mellitus and hypertension were found to be common diseases in general practice and in a hospital SC. Oral hypoglycemic agents were the main from of antidiabetic therapy in both settings, with glibenclamide being the most commonly prescribed sulfonylurea. The types of antihypertensive drugs used were different in the two locations and varied according to the coexistence of type II diabetes mellitus. Despite some potential limitations, prescription-based surveys are an easy and economical method for surveying the occurrence of some common medical problems and the pattern of drug use in a fairly large number of patients in health institutions.

Time-domain soliton filter based on a semidissipative dual-core fiber

We propose a time-domain dual-core fiber filter that greatly reduces soliton jitters and noise power in its application to ultrahigh-speed soliton communication systems. This filter is simply a dual-core fiber that has one core with negligible loss and the other with large loss.

Unusual case of corticobasal degeneration with tau/Gallyas-positive neuronal and glial tangles

A 74-year-old woman with corticobasal degeneration (CBD) had a 9-year history of progressive loss of strength and rigidity of her right hand and then arm, followed by speech difficulties, dyskinesia, rigidity, spasticity and weakness of the ipsilateral lower limb, ultimately also involving the opposite side. She later developed supranuclear gaze palsy. Her memory remained intact during most of the duration of her disease. Laboratory tests and anti-Parkinsonian medications were not helpful. At autopsy, frontal lobe atrophy, discoloration of putamen (Pt) and pallor of substantia nigra (Sn) were observed. Neuronal loss and gliosis were extensive in motor cortex and milder in frontal cortex, abruptly ending at the central sulcus and junction of cingulate gyrus. "Achromatic" neurons were present. Neuronal loss and gliosis were seen in Pt and Sn and corticobasal inclusions in Sn. Numerous Gallyas/tau-positive, Bielschowsky/ubiquitin-negative coil, sickle, or coma-shaped tangles and thread-like processes were found in affected cortex, Pt and Sn. Some of the tangles were in neurons, but most occurred in astroglia, and their processes. The presence of Gallyas/tau-positive glia in CBD may have the same diagnostic significance as in progressive supranuclear palsy, analogous to the argyrophilic ubiquinated inclusions in oligodendroglia in multisystem atrophy. We suggest that in CBD: (1) cytoskeletal protein metabolism in neurons and glia can simultaneously be perturbed in certain neurodegenerative diseases, and (2) the astrocytosis in CBD may not be simply a reactive process but an integral part of the disease.

Accurate elasto-optic probe method for measurement of coupling length in twin-core optical fiber

The theoretical principle and experimental procedure of a new method of measuring the coupling length of a twin-core fiber are presented. This method is simple, nondestructive, and gives direct results without extensive data processing. It is based on the elasto-optic technique and had a very good spatial resolution so that coupling lengths of the order of a few millimeters can be measured. We show how this method can be applied to the measurement of the polarization coupling of birefringent noncircular twin-core fibers.

Narrow-bandpass filter with gain by use of twin-core rare-earth-doped fiber

We demonstrate both numerically and experimentally that rare-earth-doped twin-core fiber couplers can function as a narrow-bandpass wavelength filter or as a demultiplexer. The experimental bandwidth obtained is 6.5 nm. In addition, the filtered signal experiences a gain of 20 dB instead of attenuation.

Analytical solution to soliton switching in nonlinear twin-core fibers

We give an approximate analytical solution to the coupled nonlinear Schrödinger equations that govern the soliton switching in a nonlinear fiber coupler. We have derived, in simple analytical form, the switching condition by which solitons can be switched from one core to another. The analytical result has been checked against the numerical results, and it is found that there is close agreement.

Couplings in spun twin-core optical fibers

A new effect of spun twin-core fiber is observed in which the coupling between the two cores is increased with the spin rate. In addition, the cladding-mode attenuation is also increased. These effects can find many useful applications in fiber devices for optical communication, sensing, or signal processing.

Optical switching in twin-core erbium-doped fibers

We report the theoretical and experimental investigation of switching in a nonlinear twin-core erbium-doped fiber coupler. It is shown that switching action takes place at a power of a fraction of 1 mW. Thus it provides a practical means of fabricating an all-optical fiber switch.

Twin-core optical fiber with large core ellipticity

The first (we believe) twin-core optical fiber with large core ellipticity has been fabricated, and its significant polarization dependent coupling properties have been demonstrated.