Biomedical subjects

V Havu

Publications and source records attributed to V Havu.

8 recordsLinked to original sources

PubMed2006

Finite-element implementation for electron transport in nanostructures.

We have modeled transport properties of nanostructures using Green's-function method within the framework of the density-functional theory. The scheme is computationally demanding, so numerical methods have to be chosen carefully. A typical solution to the numerical burden is to use a special basis-function set, which is tailored to the problem in question, for example, the atomic-orbital basis. In this paper we present our solution to the problem. We have used the finite-element method with a hierarchical high-order polynomial basis, the so-called p elements. This method allows the discretation error to be controlled in a systematic way. The p elements work so efficiently that they can be used to solve interesting nanosystems described by nonlocal pseudopotentials. We demonstrate the potential of the implementation with two different systems. As a test system a simple Na-atom chain between two leads is modeled and the results are compared with several previous calculations. Secondly, we consider a thin hafnium dioxide (HfO2) layer on a silicon surface as a model for a gate structure of the next generation of microelectronics.

Journal Article↗

PubMed2000

A double-blind, randomized study to compare the efficacy and safety of terbinafine (Lamisil) with fluconazole (Diflucan) in the treatment of onychomycosis.

In a randomized, double-blind, double-placebo, multicentre study, terbinafine 250 mg daily for 12 weeks was compared with fluconazole 150 mg once weekly for 12 or 24 weeks in the treatment of onychomycosis. A total of 137 patients with culture-confirmed onychomycosis was divided into three groups: group A received terbinafine for 12 weeks, group B received fluconazole for 12 weeks, while group C received fluconazole for 24 weeks. At completion of the study (week 60), the mycological cure rate was higher in the terbinafine group than in the fluconazole groups: 89% vs. 51% and 49%, respectively (P < 0.001). The length of unaffected nail increased until week 24 in group B and until week 36 in group C, but was still increasing in group A at the final visit (week 60). Complete clinical cure of the target nail at week 60 was 67% in the terbinafine group, compared with 21% and 32% in the fluconazole groups, respectively. The incidence of adverse events was low for both study agents. We conclude that terbinafine 250 mg daily for 12 weeks is significantly more effective in the treatment of onychomycosis than fluconazole 150 mg once weekly for either 12 or 24 weeks.

Adolescent↗

PubMed1999

Continuous and intermittent itraconazole dosing schedules for the treatment of onychomycosis: a pharmacokinetic comparison.

This multicentre, double-blind, randomized study compared the pharmacokinetics of itraconazole given at 200 mg once daily for 3 months and intermittently at 200 mg twice daily for 1 week per month followed by a 3-week drug-free period for 3 months in the treatment of onychomycosis. Patients were followed for 9 months after treatment. Itraconazole and hydroxy-itraconazole plasma concentrations and itraconazole nail tip concentrations were determined at regular intervals. With intermittent therapy (n = 64), increases of consistent magnitude were seen in the mean itraconazole and hydroxy-itraconazole plasma concentrations at the end of each 1-week treatment phase; values returned towards baseline during each subsequent 3-week drug-free period. The mean concentration of itraconazole in fingernail tips increased steadily from week 4, reached a maximum value at week 24 (213 ng/g), declined sharply between weeks 24 and 36 and returned to baseline by week 48; the mean concentration profile was similar for toenail tips (maximum value 305 ng/g at week 24) but decreased at a slower rate. With continuous therapy (n = 65), steady-state mean plasma concentrations of itraconazole and hydroxy-itraconazole were obtained within 4-5 weeks of the start of treatment and remained reasonably constant between weeks 4 and 12. The mean concentration of itraconazole in fingernail tips reached a maximum value at week 12 (524 ng/g) and returned towards baseline by week 48; in contrast, the maximum mean concentration of itraconazole in toenail tips was 698 ng/g at week 36 and did not return to baseline by week 48. No clear relationship was observed between response to treatment and concentration of itraconazole or hydroxy-itraconazole in plasma or itraconazole in nails, suggesting that concentrations exceeded therapeutic levels. In conclusion, intermittent therapy resulted in higher maximum itraconazole plasma concentrations but lower total drug exposure, and hence lower itraconazole nail concentrations, than continuous therapy. However, the intermittent schedule was not associated with a lower cure rate, which indicates that itraconazole nail concentrations remained within the therapeutic range.

Adolescent↗

PubMed1997

Itraconazole therapy is effective for pedal onychomycosis caused by some nondermatophyte molds and in mixed infection with dermatophytes and molds: a multicenter study with 36 patients.

BACKGROUND: Onychomycosis of the toenail caused by nondermatophyte molds alone or in combination with dermatophytes is difficult to eradicate with standard antifungal therapy. OBJECTIVE: Our purpose was to determine the effectiveness of itraconazole in the treatment of toenail onychomycosis caused by molds alone or in combination with dermatophytes. METHODS: We treated 36 patients with this drug given as continuous dosing (100 or 200 mg/ day) for 6 to 20 weeks or as a 1-week pulse dosing (200 mg twice daily for 1 week per month) for two to four pulses. RESULTS: Patients with toenail onychomycosis with the following organisms were treated: Aspergillus spp. (eight patients), Fusarium spp. (four patients), Scopulariopsis brevicaulis (23 patients), and Alternaria spp. (one patient). Nineteen patients had onychomycosis with a mixed origin. At follow-up, 12 months after therapy was initiated, clinical and mycologic cure was achieved in 15 of 17 patients (88%) with onychomycosis caused by a single mold. In patients with mixed infection, a clinical cure was obtained in 16 of 19 patients (84%) and a mycologic cure in 13 of 19 patients (68%). CONCLUSION: Itraconazole appears to be effective and safe for the treatment of toenail onychomycosis caused by some nondermatophyte molds alone or in combination with dermatophytes.

Antifungal Agents↗

PubMed1997

A double-blind, randomized study comparing itraconazole pulse therapy with continuous dosing for the treatment of toe-nail onychomycosis.

In this multicentre, double-blind, parallel group study, we evaluated the efficacy and safety of continuous treatment with itraconazole, 200 mg daily for 3 months, in comparison with itraconazole pulse therapy, 400 mg daily 1 week per month for 3 months, in the treatment of toe-nail onychomycosis. The study included 129 patients with distal subungual onychomycosis of the toe-nails, confirmed by microscopy and positive for dermatophyte culture; 65 received continuous treatment and 64 received pulse therapy. Patients were followed up for 9 months after treatment. After 12 months, there were 62 evaluable patients in the continuous group and 59 evaluable patients in the pulse group. The clinical response (i.e. the size of the affected area and the progress of the infection) and mycological cure (i.e. negative results on microscopy and culture) were the main outcome measures. A clinical response was defined as a cure or a marked improvement. Clinical response rates were 69%, in the continuous group, and 81% in the pulse group at month 12; the corresponding mycological cure rates were 66 and 69%. A better improvement in signs and symptoms was noted in the pulse group. Six patients were withdrawn from treatment because of adverse events, not all of which were thought to be drug-related. There were no clinically relevant laboratory abnormalities. We conclude that both regimens are effective, safe and well tolerated. The superiority of one treatment over the other was not established, but the results tended to favour pulse therapy. Equivalence testing confirmed that pulse therapy was at least equivalent to continuous treatment.

Adolescent↗

PubMed1994

Lowered peripheral resistance in arteries of legs with venous ulcer.

In the literature there is disagreement concerning the existence of arteriovenous shunting in legs with venous ulcer(s). The aim of this study was to find out if there are differences in resistance in the arteries of ulcer legs and non-ulcer legs and if it is possible to investigate this with a non-invasive Doppler method. Eleven patients, aged 34-87 years, with venous ulcer only in one leg, were investigated using angiography and duplex scanning. Angiography showed premature venous filling and Doppler examination showed lowered peripheral resistance in the arteries of every ulcer leg. Lowered peripheral resistance was found only in one non-ulcer leg, which, however also had signs of venous stasis. Our results clearly show that there is lowered peripheral resistance in arteries of legs with venous stasis. The possible significance of this phenomenon in the pathogenesis of venous leg ulcer is discussed.

Adult↗

PubMed1992

Efficacy and safety of itraconazole in the long-term treatment of onychomycosis.

Sixty-one patients with a clinical diagnosis of onychomycosis in finger or toe nails were treated with itraconazole 100 mg/day or griseofulvin 500 mg/day for six to nine months. The infective causes were Trichophyton rubrum, Trichophyton mentagrophytes, or Trichophyton violaceum, and in two cases Candida albicans. A total of 27 finger and 390 toe nails were infected. Statistically significant intragroup reductions from baseline symptom severity values were seen at endpoint (month 6 or 9) for both treatment groups for all parameters: colour change, thickness, brittleness and unaffected area. No clinically or statistically significant differences between the treatment groups were seen at endpoint. However, the itraconazole group continued to improve during the follow-up, while the mean symptom severity ratings remained the same in the griseofulvin group. All itraconazole patients and 85% of griseofulvin patients were rated as cured or markedly improved at endpoint. Nineteen out of 26 evaluable itraconazole patients (73%) remained cured during the three month follow-up period, compared with 12 out of 17 griseofulvin patients (71%). The rather large number of drop-outs, especially among griseofulvin patients, makes it difficult to draw definitive conclusions of the symptom recurrence. Two itraconazole patients stopped medication due to an adverse event, compared to four patients in the griseofulvin group. The clinical laboratory data on itraconazole-treated patients did not show any statistically or clinically significant changes. In conclusion, itraconazole was at least as effective as griseofulvin in the treatment of onychomycosis. The itraconazole group continued to improve after the treatment was stopped. The results show that itraconazole 100 mg/day is safe and efficient in the long-term treatment of fungal nail infections.

Adolescent↗

PubMedDate not supplied

Malassezia furfur colonization of neonates in an intensive care unit.

We studied Malassezia furfur colonization of neonates in the neonatal intensive care unit (NICU) and found that the rate was astonishingly high as compared to the previous studies. In very low birth weight (less than 1,000 g) infants we recorded a colonization rate of 80%, and 4% infants with a birth weight greater than 2,000 g. Under 10 day's hospitalization the rate was 11%, and it was 70% after 20 days spent in the unit. Among the infants with the birth weight less than 1,700 g, antibiotic therapy was recorded as a significant risk factor for colonization. In the infants with a greater birth weight, the colonization rate was independent from the risk factors studied. M. furfur colonization could not be linked with occurrence of any symptoms of signs recorded and colonization by M. furfur was so common in NICU that the predictive value of surveillance cultures is poor.

Birth Weight↗