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Biomedical subjects

L M David

Publications and source records attributed to L M David.

At least 19 recordsLinked to original sources
PubMed2005

Wet-weather urban discharges: implications from adopting the revised European Directive concerning the quality of bathing water.

Wet weather urban discharges are responsible for bathing water contamination. The proposal for a revised EU Directive concerning the quality of bathing water imposes significantly more stringent requirements for the management of bathing water quality, with particularly important repercussions on beaches subjected to short-term pollution incidents. The paper reviews the aspects from EU legislation most directly related to the problem of wet-weather discharges, placing special emphasis on the recent revision process of the Directive on bathing water quality, and evaluates the benefits of some potential solutions based on continuous modelling of a combined sewer system. Increasing the sewer system storage capacity or the STP hydraulic capacity may substantially reduce the untreated discharge volumes, but spill frequency reductions under 2 to 3 spill days per bathing season will hardly be achieved. Results show the severe strains that local rainfall patterns would place on compliance with the Commission's proposal for a revised Directive and highlight the importance of the changes introduced in the amended proposal recently approved by the Council, making it less prescriptive if adequate measures are adopted to prevent bathers' exposure to short-term pollution incidents.

Baths↗
PubMed2005

Combined sewer overflow emissions to bathing waters in Portugal. How to reduce in densely urbanised areas?

The current proposal for a revised European Directive concerning the quality of bathing water significantly increases the demands for the control of wet-weather discharges. A densely urbanised combined catchment was modelled for a 19-year long rainfall series in order to assess the current situation and to evaluate the benefits of potential solutions. Storage and advanced physical-chemical treatment of stormwater in the STP may significantly contribute for the reduction of the overflow volumes but reductions of the spill frequency under 2.5 spill days per bathing season are hardly obtained. This study reveals the severe strains that the local rainfall pattern may place on the control of the frequency of wet-weather discharges, pointing to serious technical, social and economical implications, at the local and at the national level, if the current proposal for a revised European Directive on Bathing Water is enforced.

Cities↗
PubMed2002

Wet weather water quality modelling of a Portuguese urban catchment: difficulties and benefits.

This paper discusses the use of water quality deterministic modelling together with an integrated approach to assess the impact of urban stormwater discharges into ephemeral watercourses, based on the study of a Portuguese catchment. The description of the main aspects, difficulties and benefits found during data collection and model calibration and verification is presented, and the associated uncertainties and errors discussed. Experimental results showed a strong short- and long-term impact of sewer discharges on rivers, and confirmed deposition, resuspension and transport of pollutants as important processes for the water quality. However, the resuspension of riverbed sediment pollutants during storms was probably more significant than the direct impact of the urban discharges. The HydroWorks model was used since it allows for the calculation of pollutant build-up on catchment surfaces and in gully pots, their wash-off, and the deposition and erosion of sediments in sewers. However, it uses several constants, which could not be independently calibrated, increasing the uncertainty already associated with the data. River flows have quite different magnitude from the sewer system overflows, which, together with the difficulties in evaluating river flow rates, makes the integrated modelling approach rather complex and costly.

Cities↗
PubMed1999

Laser resurfacing: a safe and predictable method of skin resurfacing.

Skin resurfacing with lasers for skin restoration has been the most exciting advance in cosmetic surgery in the past 2 years. This method has effectively replaced chemical peel and dermabrasion as modes for skin rejuvenation, yet surprisingly, very little has been published on its effectiveness. Our aim is to delineate clear indications, methods and results of laser skin resurfacing. Laser resurfacing has evolved over the past 13 years and our current method has emerged from this experience. This method has been employed on 258 consecutive patients treated over the past 2 years. A total of 201 patients were treated for photodamaged skin, 53 for facial acne scarring and four for post-surgical scars. Each of these conditions has in common the pathological finding of contour irregularity of the involved abnormal skin. The CO2 Ultrapulse laser's advantage is the predictable ability to vaporize the upper layer of elevated skin, tighten collagen bundles and induce a local inflammatory reaction with epithelial proliferation. This paper presents a clear, concise, and conservatively oriented technique, including pre- and post-operative care of laser skin resurfacing. The technique presented is conceived to correct precisely the underlying pathological condition and can be used in conjunction with other cosmetic procedures. A total of 200 patients underwent full face resurfacing, 41 periorbital, 13 perioral and four for facial scars. Of the patients, 78% were female and 22% were male. The results of each patient were judged by an independent observer. Some 92% were found to have either an excellent or very good result; 2% were judged to be satisfactory; and 6% were from outside the region or were lost to follow-up. Minor complications included 12% transient post-inflammatory hyperpigmentation, 3% acute acne and 1% herpes type 1. There were no major complications, including hypertrophic scarring. A total of 15% required some type of secondary touch-up resurfacing. Our method of laser skin resurfacing offers a consistent method for dramatic improvement of facial skin quality for those patients with photodamage and acne scarring, while minimizing risk.

Acne Vulgaris↗
PubMed1999

Diagnostic tests and specimens used to screen for Chlamydia trachomatis in genitourinary medicine clinics in the United Kingdom.

This questionnaire study looked at the diagnostics tests and specimens used to screen for Chlamydia trachomatis in UK genitourinary medicine (GUM) clinics. Replies were received from 70% (185/265) of clinics. Half used only one site to screen women. One-third took anal swabs from patients who had anal sex and 10% took oropharyngeal swabs from patients who had oral sex. Immunoassays were used to screen men for chlamydia in 86% of the clinics and women in 88%. Only 60% of male and 62% of female immunoassays were supplemented by a second test. Six per cent of clinics used molecular technique (MT) to screen men and 4% to screen women and 4% were trying to acquire it. Culture was not available to 58% of clinics. MT was not available to 81%, 89% of which was due to non provision locally and/or cost. Only 7% of clinicians thought that using MT for screening was unnecessary. There were significant differences in the availability of the technique between large academic and small clinics. A national review of GUM strategies to screen for C. trachomatis with adequate funding is urgently needed.

Chlamydia Infections↗
PubMed1999

In my hands...

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed1997

Genital colonisation and infection with candida in heterosexual and homosexual males.

OBJECTIVES: To determine the penile, perianal, and oropharyngeal candidal colonisation rates among homosexual and heterosexual males attending an STD clinic. To determine the prevalence of balanitis and candidal balanitis in the two groups. SUBJECTS: 252 heterosexual and 210 homosexual male patients attending consecutively the STD clinic in Coventry, England. DESIGN: A prospective study recording sexual behaviour, relevant history, symptoms, and examination. Specimens for candida culture were collected from the glans penis, perianal area, and oropharynx. RESULTS: Among the 462 men studied, penile, perianal, and oropharyngeal colonisation rates were 74 (16%), 70 (15%), and 116 (25%) respectively. On examination, 47 (10%) were found to have balanitis. Of the 74 patients with penile colonisation, 26 (37%) were symptomatic and 20 (27%) had balanitis. The 223 heterosexual and the 196 homosexual males who had sexual intercourse within 3 months had comparable colonisation rates of candida on the penis, perianal area, and oropharynx. Balanitis was seen in 31 heterosexuals (14%) and candidal balanitis in 16 (7%); the incidence was significantly less in homosexuals where balanitis was seen in 12 (6%) and candidal balanitis in four (2%). CONCLUSIONS: Itching or burning sensations after sex were the most common symptoms associated with penile colonisation with candida and were present in more than one third. Candidal balanitis was commoner in those who had vaginal than those who had anal intercourse within 3 months.

Adolescent↗
PubMed1997

Gonorrhoea in Coventry 1991-1994: epidemiology, coinfection and evaluation of partner notification in the STD clinic.

The aim of this study is to analyse the epidemiology of gonorrhoea in the Coventry area between 1991-1994 and the implementation and outcome of partner notification. A total of 404 episodes in 382 patients comprised the study group. In Coventry, 97% of episodes were managed in the STD clinic. There was a decrease in female and heterosexual male cases from 172 cases in 1991 to 37 cases in 1994 and increase in homosexual male cases from 8 in 1991 to 13 in 1994 (P<0.0001). Chlamydial coinfection was found in 38%. Among patients with gonorrhoea, 33% were asymptomatic and 40% with gonorrhoea and chlamydia were asymptomatic. Ten per cent of index cases were asymptomatic as were 83% of contact cases (P<0.0001). The health advisers (HAs) interviewed 82% immediately and 94% at some time after diagnosis. Of the average 1.5 partners per patient identified, 0.31 partners per patient were already screened, another 0.4 partners per patient were traced, 0.37 partners per patient were not traced, and for 0.41 partners per patient notification outcome was unknown or unconfirmed. Partner notification of 278 index cases traced 163 primary or tertiary contacts, 115 were new cases of gonorrhoea.

Adolescent↗
PubMed1996

Penetration depth of Ultrapulse carbon dioxide laser in human skin.

BACKGROUND: Recent technological advances have dramatically increased the use of lasers in skin resurfacing. The first high-power short-pulse laser, Ultrapulse, has found extensive use in dermatology and plastic surgery for skin resurfacing. Reports for penetration depth are at best anecdotal. To our knowledge this is the first report of histological effects of the Ultrapulse in human skin. OBJECTIVE: To determine the effect of single and repeated (two or three) Ultrapulse laser impacts on volar forearm skin. METHOD: The volar surface of the arm in four patients received in adjacent areas either one, two, or three pulses, after anesthesia. The treated areas were immediately biopsied, hematoxylin & eosin prepared, and examined. RESULTS: Increasing the number of passes correlates with increased depth of penetration and thermal ablation. No significant propagation of destructive thermal energy to adjacent tissue was noted. CONCLUSION: One impact at the tested parameters ablated most of the epidermis. Two impacts superimposed ablated the entire epidermis and the superficial papillary dermis. Three superimposed impacts penetrated to the reticular dermis.

Adult↗
PubMed1996

Urinary symptoms, sexual intercourse and significant bacteriuria in male patients attending STD clinics.

OBJECTIVE: To assess the relationship between sexual behaviour, urinary symptoms, urinalysis and bacteriuria in men attending STD clinics. DESIGN: A prospective study recording sexual behaviour, urinary symptoms and collecting mid-stream urine specimens. SETTING: Two West Midlands STD clinics, UK. SUBJECTS: 1086 new male patients. RESULTS: 704 patients had had sexual intercourse (SI) within 14 days of testing, 424 had urinary symptoms and 122 had pyuria. All 13 patients with positive culture had SI < 14 days before testing, urinary symptoms and pyuria. No association was found between sexual orientation, type of SI, number of sexual partners, condom usage and bacteriuria. CONCLUSION: Bacteriuria does not behave as an STD but SI may be a factor in acquiring bacteriuria. Dysuria with or without urethral discharge is the most predictive symptom of bacteriuria. Pyuria has a high sensitivity for predicting bacteriuria among males.

Adolescent↗
PubMed1995

Rapid laser scanning for facial resurfacing.

BACKGROUND: Laser skin resurfacing is growing in popularity in both the professional as well as lay populations. Freehand delivery of impacts is relatively time consuming. Accurate and precise placement of impacts to avoid unwanted overlapping and the superimposing of multiple impacts is difficult. OBJECTIVE: To evaluate a new computerized scanning device, the computerized pattern generator (CPG), and to compare it with freehand delivery of multiple laser impacts over large areas. METHODS: Sixty-one patients were treated using the CPG by surgeons who are experienced with freehand laser resurfacing. RESULTS: CPG delivery provides more rapid resurfacing with more uniform, accurate, and precise distribution of impacts. CONCLUSION: Combining the CPG with the Ultrapulse laser is a valuable addition making the procedure faster and more controllable.

Adult↗
PubMed1995

Laser-assisted rhytidectomy. A preliminary report.

BACKGROUND: The carbon dioxide (CO2) laser is a surgical tool recognized for its capacity of combined simultaneous tissue transection and hemostasis without unwanted distant transmission of energy. OBJECTIVE: To determine the potential of laser-assisted rhytidectomy. METHODS: A preliminary group of 18 patients were treated for facial rejuvenation by a technique of laser-assisted rhytidectomy with excellent results. RESULTS: No major complications including hematoma were seen. CONCLUSION: Based on these initial findings, we conclude that laser-assisted rhytidectomy shows great promise for better results with diminished risks.

Adult↗
PubMed1994

Laser hair transplantation.

BACKGROUND: A new ultrapulse CO2 laser has been investigated for its possible use in hair transplanting. This laser, because of its ultrashort high energy pulses, produces far less thermal damage to adjacent tissues, including hair follicles, than earlier types of CO2 lasers. The potential advantages of using such a laser in minigrafting are reviewed and include less bleeding, greater density, and absence of "compression." OBJECTIVE: The purpose of this study was to see if hair survival in grafts placed into laser-prepared sites would be as good or better than that seen with scalpel slits. METHOD: Hair counts were used in 10 patients to compare hair survival in grafts placed into laser-prepared sites and into scalpel-prepared sites in a comparable but contralateral location. RESULTS: Average graft hair counts were greater in laser-prepared sites in four of 10 patients, equal to grafts in scalpel-prepared sites in five, and fewer in one. Hair growth occurred earlier in laser-prepared sites in five of the 10 patients. CONCLUSION: The authors are optimistic that the ultrapulse laser will become an important tool in hair transplanting.

Hair↗