Biomedical subjects
D R Williams
Publications and source records attributed to D R Williams.
Loop diathermy excision of the cervical transformation zone in patients with abnormal cervical smears.
OBJECTIVE: To determine the efficacy and morbidity of fine loop diathermy excision of the cervical transformation zone as applied to the management of outpatients with abnormal cervical smears. DESIGN: Prospective programme trial with six month follow up. SETTING: Two hospital based colposcopy clinics. PATIENTS: 616 Patients aged 16-60 with abnormal cervical smears. INTERVENTIONS: After colposcopic and cytological assessment excision of the cervical transformation zone by fine loop diathermy under local anaesthesia in the outpatient department. MAIN OUTCOME MEASURES: Time to complete the treatment, immediate morbidity in terms of discomfort and bleeding, and cytological and colposcopic findings at six months. RESULTS: Treatment was completed in a mean of 3.47 minutes (SD 1.99). Immediate morbidity was minimal, and histological specimens were adequate in over 90% of cases. Almost two thirds of patients were treated at their first visit to the clinic. 58 Patients (9.4%) failed to attend for follow up at six months and one had had a hysterectomy. Of the 557 patients who attended for colposcopic and cytological follow up at six months, 506 (91%) were normal cytologically and 19 (3.4%) had histologically confirmed persistence of cervical intraepithelial neoplasia. The overall confirmed failure rate of the technique was 4.4%. CONCLUSION: Loop diathermy excision is an effective treatment with low morbidity and is an appropriate modality for patients with abnormal cervical smears.
Consequences of spatial sampling for human motion perception.
This paper describes evidence for spatial aliasing in human motion perception. For a certain range of spatial frequencies, interference fringes drifting across the extrafoveal retina resemble two-dimensional spatial noise drifting in the opposite direction. For retinal locations within 10 deg of the fovea, the perceived direction of motion is veridical up to spatial frequencies near the cone Nyquist frequency, reverses between one and two times the cone Nyquist frequency, and sometimes reverses back to the correct direction at still higher frequencies. Thus two "motion nulls", or spatial frequencies at which the direction of motion is ambiguous, are typically observed at each retinal eccentricity. A computational model is described in which sinusoidal gratings are sampled by a cone mosaic and the direction of motion of the filtered output is computed. The model predicts that the second motion null, but not the first, should be relatively immune to postreceptoral processing and should roughly equal twice the cone Nyquist frequency. This prediction is confirmed by psychophysical experiments, providing a new technique to estimate cone spacing in the living human eye.
Tetanus immunization status and immunologic response to a booster in an emergency department geriatric population.
STUDY OBJECTIVES: Although effective procedures for the prevention of tetanus have long been available, serosurveys done since 1977 demonstrate that 49% to 66% of the elderly population lacks a protective antitoxin level (more than 0.01 IU/mL). This study was undertaken to assess the tetanus immunization status of patients presenting to an emergency department and to evaluate their immunologic response to a tetanus booster. SETTING: The study was conducted in a tertiary care ED. TYPE OF PARTICIPANTS: The patients enrolled were 65 or more years old and had breaks in their skin barriers. DESIGN: At each patient's initial presentation, pertinent demographic data and tetanus immunization history were recorded. The patient was then followed for 21 days. INTERVENTIONS: Each patient's antitoxin titer was determined on a serum sample by ELISA, and, if required by the Advisory Committee on Immunization Practices criteria, a booster was administered at the first visit. MEASUREMENTS AND MAIN RESULTS: Serum antitoxin assays were repeated on days 7, 14, and 21 after the initial visit until seroconversion (titer more than 0.01 IU/mL). Forty-four patients (55%) had protective levels at initial presentation, and in 36 (45%) the levels were not protective. Age and sex were not predictive of protection. Past military service and a definite history of three or more previous immunizations were good predictors of protection. Of 34 patients who were followed serially for inadequate initial titers, only 19 (56%) seroconverted by day 14. Patients who did not seroconvert were more likely to be older (P less than .05). CONCLUSIONS: This study demonstrated that a significant number of elderly patients lacked an initial protective level of tetanus antitoxin. Of these, 44% failed to seroconvert within 14 days and carried a potential risk of developing tetanus.
Conjugative plasmid transfer from Escherichia coli to Clostridium acetobutylicum.
The conjugation mechanism of IncP plasmids may be employed to mobilize small non-conjugative plasmids from Escherichia coli to a wide range of different organisms. This strategy has been adapted for use with the Gram-positive anaerobe, Clostridium acetobutylicum NCIB 8052. Several shuttle vectors containing replicons from pAM beta 1 (Enterococcus faecalis), pCB101 (Clostridium butyricum) or pWV01 (Streptococcus cremoris), together with the cis-acting oriT region of RK2, have been constructed, and transferred to and established in this organism. One of the vectors apparently contains a hot spot for insertion of IS1. Conjugative mobilization of plasmids from E. coli will provide a useful alternative to electroporation for effecting gene transfer to this industrially important anaerobe.
A three-year evaluation of the quality of diabetes care in the Norwich community care scheme.
The care of patients with diabetes was assessed in eight general practices intending to establish mini-clinics. Seven of these practices subsequently participated in a mini-clinic scheme incorporating continuing education and audit. After 3 years further data were collected and compared with the baseline assessment. Seven other local practices which had not set up mini-clinics were also studied. During the time between the baseline survey and the 3-year assessment the proportion of non-insulin-treated patients registered with the mini-clinic practices and receiving regular review in general practice increased from 54 to 84%. The proportions of patients with a record of body weight, blood pressure, urinary glucose, urinary protein, blood glucose, HbA1, visual acuity, examination of the fundus through dilated pupils, examination of the feet, and a consultation with a dietitian within the previous year increased significantly and were higher in mini-clinic than in comparison practices although, for a substantial number of patients in both groups of practices, these remained unrecorded. This study shows that organized and audited general practice mini-clinics can improve the process of care for diabetic patients.
Prevention of post-cone biopsy cervical stenosis using a temporary cervical stent.
Stenosis of the residual cervix is not an infrequent complication of cone biopsy which may result in subfertility, problems with adequate follow-up and dysmenorrhoea. In an attempt to minimize this complication a temporary indwelling cervical support stent has been developed. This is sutured into the exposed cone bed immediately after cutting the cone specimen and removed 2 weeks later. A pilot study using this device in 33 cold knife conizations has been performed. There were no primary or secondary haemorrhages and no post-conization pelvic infections. At follow-up, 6 months after cone biopsy two patients (6%) had clinical cervical stenosis, and one patient (3%) complained of dysmenorrhoea (although the cervix was not stenosed). The cervical transformation zone was fully visible in 21/33 patients (64%) (95% CI 48 to 80) and follow-up smears contained endocervical cells in 20/33 patients (61%) (95% CI 44 to 78). These results compare very favourably with historical controls from the same unit and suggest that cone biopsy support stents should now be assessed in a prospective randomized trial.
Parenteral nutrition. Pharmaceutical problems of compatibility and stability.
A typical All-in-One (AIO) parenteral nutrition mixture in a 3-litre polymeric infusion bag will consist of lipid emulsion, amino acids, glucose, electrolytes, trace elements and vitamins. This varied mixture of chemical entities provides the potential for a number of chemical and physicochemical interactions that can compromise the clinical safety and efficacy of the product. The destabilisation of the lipid emulsion in the presence of electrolytes is a major problem. Although a predictive equation for the maximum concentrations of mono-, di- and trivalent ions causing instability has been proposed, it is too simplistic to be of significant value. The reasons for this are discussed as well as the stability implications of other additives to the parenteral nutrition mixture.
Citreamicins, novel antibiotics from Micromonospora citrea: isolation, characterization, and structure determination.
A new family of antibacterial antibiotics has been isolated from Micromonospora citrea. The compounds, designated citreamicins alpha, beta, gamma, zeta and eta are of the polycyclic xanthone structure type. Their isolation, characterization and structure determination are presented.
Mechanical analysis of the factors affecting dynamization of the Orthofix Dynamic Axial Fixator.
Loading trials were conducted to identify mechanical factors affecting dynamization of a commercially available external fixator (Orthofix) that is designed to undergo free telescopic motion when axially loaded. Angular variations between the proximal and distal screw clamps and the telescoping fixator body failed to produce fixator binding (failure to dynamize) in any of the loading trials. However, binding was produced by applying external torques in magnitudes that occasionally occur during routine ambulation. The specific torque necessary to induce binding (typically 3-4 Nm) was only a weak function of axial load magnitude, axial loading frequency, or simulated fracture stiffness. Among several geometrical variables of fixator application, only the pre-extension of the telescoping body and circumferential misalignment between proximal and distal pin clusters had an appreciable influence on the threshold binding torque. Axial fixator motions were also monitored in a small adjunct clinical series of 22 dynamized tibial fractures. The fixator dynamized appropriately in 15 cases (68%). Three patients (14%) showed evidence of fixator binding, and another four (18%) had less than predicted slider excursions. The role of several design factors implicated in torque-induced fixator binding is discussed in light of the benchtop and clinical observations.
Process-scale reversed-phase high-performance liquid chromatography purification of LL-E19020 alpha, a growth promoting antibiotic produced by Streptomyces lydicus ssp. tanzanius.
LL-E19020 alpha is a novel antibiotic produced by fermentation of the soil microorganism Streptomyces lydicus ssp. tanzanius. The compound is highly effective in inducing increases in weight gain and feed conversion efficiency in livestock. In order to obtain kilogram quantities of the material for field trials, pilot plant scale fermentations (up to 7500 l) were carried out. The antibiotic was recovered from the fermentation broth by solvent extraction. The resultant crude extract was subjected to reversed-phase (C18) chromatography on a process-scale high-performance liquid chromatography (HPLC) unit. The heart of the instrumentation is the Millipore Kiloprep chromatograph with the standard 12-l cartridge column. The laboratory housing the chromatograph has been specifically designed for this work. Tanks for mobile phase preparation are mounted on load cells for precise measurement of components. In this explosion-proof laboratory, all solvent handling areas are well ventilated and a separate breathing air system is provided for the operators. For the purification of the LL-E19020 antibiotics, the mobile phase consisted of a gradient of acetonitrile in 0.1 M ammonium acetate at pH 4.5. The effluent was monitored by UV absorbance at 325 nm. Fractions were collected across the peaks of interest and these were analyzed by analytical HPLC. The maximum yield of LL-E19020 alpha obtained in a single run was approximately 100 g. The antibiotic was recovered from the mobile phase by extraction with methylene chloride. The methylene chloride phase was concentrated under reduced pressure to yield a gummy residue which was finally freeze-dried from tertiary butanol to yield an off-white solid suitable for blending with various feed components.
Parenteral and partial enteral nutrition, essential fatty acids and trace elements.
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Prevalence of diabetes in a predominantly Asian community: preliminary findings of the Coventry diabetes study.
To assess the prevalence of both diagnosed and undiagnosed diabetes mellitus in an area of predominantly Asian population the Coventry diabetes study is carrying out house to house screening for diabetes in people aged 20 and over in Foleshill, Coventry. In the first five of 12 areas to be studied 2130 of 2283 Asian (93.3%) and 1242 of 1710 white subjects (72.6%) aged 20-79 agreed to be screened. The prevalence of diabetes adjusted to 1987 demographic estimates was 11.2% in Asian men and 8.9% in Asian women whereas it was 2.8% in white men and 4.3% in white women. The excess of diabetes in Asian subjects was predominantly of non-insulin-dependent diabetes, and no significant differences in body mass were found to account for the higher prevalence. Diabetes had not been diagnosed previously in at least 26% of the white and 30% of the Asian diabetics screened, and it is estimated that in this community the condition remains undiagnosed in 42% of white and 40% of Asian diabetics.
A case of glandular intraepithelial neoplasia involving the cervix and vagina.
A case of high grade glandular intraepithelial neoplasia (GIN) of the vagina is described. This lesion developed 5 years after hysterectomy, which had been carried out because of histologically incomplete excision of cervical adenocarcinoma in situ, despite two conizations. The vaginal lesion was treated by local excision and subsequent radiotherapy to the vagina. The literature contains reference to only one case of vaginal adenocarcinoma in situ, which was successfully treated by local excision. The possible histogenesis of this lesion is discussed and recommendations made for follow-up of patients who have received treatment for high grade cervical or vaginal GIN.
Breast cancer screening programmes: the development of a monitoring and evaluation system.
It is important that the introduction of breast screening is closely monitored. The anticipated effect on breast cancer mortality will take 10 years or more fully to emerge, and will only occur if a succession of more short-term end points are met. Data from the Swedish two-county randomised trial provide targets that should be achieved, following a logical progression of compliance with the initial invitation, prevalence and stage distribution at the prevalence screen, the rate of interval cancers after the initial screen, the pick-up rate and stage distribution at later screening tests, the rate of interval cancers after later tests, the absolute rate of advanced cancer and finally the breast cancer mortality rate. For evaluation purposes, historical data on stage at diagnosis is desirable; it is suggested that tumour size is probably the most relevant variable available in most cases.
Outcome indicators for diabetes services--what do we have and what do we need?
Minimizing the need for hospital admissions for hyperglycaemic coma, hypoglycaemic coma and amputation of the lower limbs in patients with diabetes can be regarded as some of the legitimate objectives of a local diabetes service. Routinely collected data are available to calculate rates for such admissions for health service districts and for regions or their equivalents. East Anglian regional rates for admissions mentioning hyperglycaemic coma fell between 1981 and 1986 while rates for those mentioning hypoglycaemic coma rose. Amputation rates remained steady. Between-district variation for all rates was considerable and certain districts showed consistently high rates from year to year for hyperglycaemic coma with others having consistently high rates for amputations. Lack of standardization of case definition and uncertainty about the validity of routinely collected hospital admission data are the most important drawbacks of this approach. With careful interpretation, however, these data provide a possible source for the measurement of the effectiveness of local diabetes services.
Rehabilitation after hip fractures. Home and hospital management compared.
The rehabilitation of elderly patients after hip fractures is important: we report a prospective study which compares supported home rehabilitation with management in hospital in two similar groups of patients. Our results show that early discharge from hospital and home rehabilitation produces substantial savings in bed days, and also provides quicker and more effective recovery.
Calicheamicins, a novel family of antitumor antibiotics. 3. Isolation, purification and characterization of calicheamicins beta 1Br, gamma 1Br, alpha 2I, alpha 3I, beta 1I, gamma 1I and delta 1I.
Novel antitumor antibiotics, calicheamicins beta 1Br, gamma 1Br, alpha 2I, alpha 3I, beta 1I, gamma 1I and delta 1I were recovered from the fermentation broth of Micromonospora echinospora ssp. calichensis by solvent extraction, selective precipitation, normal phase, reversed phase and partition chromatography. The individual components were characterized by their UV, IR, 1H and 13C NMR spectral data.