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Biomedical subjects

J Dick

Publications and source records attributed to J Dick.

At least 55 records · Page 3Linked to original sources
PubMed1996

Aminoglycoside levels in the rabbit vitreous cavity after intravenous administration.

PURPOSE: To determine the penetration of gentamicin and amikacin into the rabbit vitreous cavity after their intravenous administration. METHODS: Gentamicin (1.6 mg/kg every 8 hours) and amikacin (6 mg/kg every 12 hours) were administered intravenously to 25 rabbits that had previously had the lens and vitreous removed from 43 eyes. For each drug, ocular inflammation was induced in one group of eyes by injection of heat-killed Staphylococcus epidermidis, while the other group was maintained as a control. Samples from the vitreous cavity were taken at regular intervals for 72 hours after beginning the intravenous medications and were analyzed for drug concentrations. RESULTS: The maximum intravitreal concentration +/- SD achieved for gentamicin was 1.8 +/- 0.5 microgram/ml. The maximum intravitreal concentration for amikacin was 8.5 +/- 3.2 micrograms/ml. Inflamed eyes demonstrated higher concentrations than did those without inflammation. CONCLUSIONS: In a rabbit model with conditions optimized to enhance penetration of antimicrobials into the vitreous cavity after intravenous administration, neither gentamicin nor amikacin penetrated sufficiently to reach potentially therapeutic concentrations consistently for either Pseudomonas or S epidermidis organisms.

Amikacin↗
PubMed1996

Tuberculosis in the community: 1. Evaluation of a volunteer health worker programme to enhance adherence to anti-tuberculosis treatment.

SETTING: A voluntary health worker project (Operation Elsies River) was started in a high incidence tuberculosis (TB) area in the Western Cape of South Africa, in order to assist the local TB Control programme with case-holding. OBJECTIVE: To evaluate the effectiveness of this group of volunteers in enhancing adherence of notified TB patients to tuberculosis treatment. DESIGN: A cohort study was conducted with 351 TB patients (203 children and 148 adults). RESULTS: The data from the child and the adult groups were analysed separately. The child group was more adherent to TB treatment than adults. The supervision option with staff dedicated to the treatment of TB, such as the clinic and the SANTA crèche, achieved better adherence results for pre-school children. The supervision modalities for adults did not differ in their adherence performance even following adjustment for confounders. CONCLUSION: The supervision option provided by the volunteers did not significantly improve the adherence of adult patients to antituberculosis treatment.

Adolescent↗
PubMed1996

Development of a health education booklet to enhance adherence to tuberculosis treatment.

Effective anti-tuberculosis chemotherapy was developed during the 1950's, yet four decades later the cure rates for tuberculosis (TB) worldwide remain unacceptably low. A major reason for the failure to eliminate TB is that many patients with active disease fail to take sufficient anti-tuberculosis medication to render a cure. This paper describes a project designed to involve clinic nurses in the process of exploring how TB patients experience their disease. Information obtained from the qualitative research process was used to develop a photonovel which can be used to supplement the education given to newly diagnosed TB patients.

Health Education↗
PubMed1996

Tuberculosis in the community: 2. The perceptions of members of a tuberculosis health team towards a voluntary health worker programme.

SETTING: A voluntary community health worker programme, in the Western Cape, South Africa, utilizing volunteers to administer directly observed therapy to tuberculosis (TB) patients. OBJECTIVE: This study describes the perceptions of health team members regarding the voluntary community health worker project. DESIGN: A qualitative, participatory research study utilizing focus groups. RESULTS: TB was perceived by the health team to be a stigmatized disease causing some patients to be reluctant to be associated with the TB control programme. Despite the project's dedicated approach to case-holding, volunteers expressed the need to develop skills in providing more comprehensive care. The volunteers appear to administer a more personalized service to TB patients and can bridge the gap between TB patients and the health agency. CONCLUSION: Sustained evaluation and support seem to be a vital tool in integrating a volunteer project into a health team approach. Its effectiveness appears to depend to a large degree on the people involved.

Adult↗
PubMed1995

Blocking of NMDA receptors during a critical stage of development reduces the effects of nerve injury at birth on muscles and motoneurones.

Blocking of NMDA receptors during a critical stage of development reduces the effects of nerve injury at birth on muscles and motoneurones. Injury to the sciatic nerve at birth causes many motoneurones to soleus and extensor digitorum longus (EDL) muscles of rats to die. This is reflected in a reduction of motor units in these muscles. In the soleus only 4 (12.3%) motor units remain while 10 (24.3%) remain in the EDL, showing that soleus alpha motoneurones are more sensitive to nerve injury at birth. Treatment with MK-801, an NMDA receptor blocker, rescues a proportion of motor units in both muscles, so that in the soleus 11 (36%) and in the EDL 17 (42%) of motor units survive. This loss of motor units results in muscle weakness and a reduction in force of both muscles. Treatment with MK-801 reduces the effect of nerve injury, so that muscles of treated animals are stronger and weigh more. Cross-sectional area and muscle fibre number in EDL muscles were assessed and found to be dramatically reduced after nerve injury at birth, so that the area was 20% of control, with only 13% of fibres remaining. Moreover the majority of the remaining EDL muscle fibres which are normally fast are converted into slow type I fibres, with 68% of fibres expressing slow myosin compared with 3% in control EDL muscles. In animals treated with MK-801 only 47% of muscle fibres are lost after nerve injury at birth, hence the area of the muscle is greater (51% of control). The change of muscle phenotype induced by nerve injury is prevented and the muscle fibre composition resembles that of normal EDL muscles in that 4% of muscle fibres express slow myosin compared with 3.5% in control EDL muscles. Thus, blocking NMDA receptors with MK-801 shortly after nerve injury at birth reduces the loss of motor units and this is directly reflected in an improved performance of the affected muscles.

Animals↗
PubMed1995

Vancomycin levels in the vitreous cavity after intravenous administration.

PURPOSE: We studied the effects of inflammation, repeated antibiotic doses, and the surgical status of the eye on penetration of vancomycin hydrochloride into the rabbit vitreous cavity after intravenous administration. METHODS: We studied three anatomic states (phakic, aphakic, and aphakic, vitrectomy-treated eyes) subdividing each into inflamed and noninflamed groups. Intravenous vancomycin hydrochloride (15 mg/kg of body weight) was administered every 12 hours for 48 hours. Eyes were harvested for the assay of vitreous cavity antibiotic levels at various intervals from one to 49 hours. We determined concentrations and calculated mean values and S.E.M. RESULTS: Therapeutic levels were not established in the vitreous cavity at any time period in the two phakic groups. At 25 hours, the inflamed aphakic eyes had concentrations of 5.05 +/- 1.9 micrograms/ml and the control noninflamed aphakic eyes 4.5 +/- 1.23 micrograms/ml; slight increases were found by 49 hours. Concentrations tested in the aphakic, vitrectomy-treated eyes at two, 13, 25, and 49 hours demonstrated progressive increases both in the inflamed eyes (5.4 +/- 2.4 micrograms/ml, 9.64 +/- 4.25 micrograms/ml, 9.2 +/- 3.96 micrograms/ml, 10.34 +/- 4.49 micrograms/ml) and noninflamed eyes (3.52 +/- 2.1 micrograms/ml, 5.4 +/- 1.96 micrograms/ml, 6.8 +/- 2.53 micrograms/ml, 8.7 +/- 5.44 micrograms/ml). CONCLUSIONS: Vitreous vancomycin concentrations in aphakic and aphakic, vitrectomy-treated eyes after intravenous administration exceed the minimal inhibitory concentrations for the usual gram-positive pathogens that create endophthalmitis, suggesting a role for intravenous vancomycin in the treatment of bacterial endophthalmitis.

Animals↗
PubMed1995

Vitreous cavity penetration of ceftazidime after intravenous administration.

PURPOSE: Penetration of ceftazidime, a third generation cephalosporin, into the vitreous cavity after intravenous administration was investigated. METHODS: Because antimicrobial penetration varies with surgical status of the eye and with inflammation, studies were conducted in phakic, aphakic, and aphakic, vitrectomized eyes in both normal and inflamed conditions. Ceftazidime 50 mg/kg was administered every 8 hours and vitreous cavity concentrations were tested at intervals from 2 to 72 hours after the initial dose. RESULTS: No penetration was found into control phakic and aphakic eyes, but drug concentrations were detected in inflamed eyes at 24 hours. Vitreous concentrations of ceftazidime in aphakic, vitrectomized eyes reached levels well above the minimal inhibitory concentration (MIC) for Pseudomonas organisms within 2 hours of intravenous administration in control eyes (8.5 micrograms/ml) and inflamed eyes (35.4 micrograms/ml). Inflammation and removal of the lens and vitreous significantly enhanced ceftazidime penetration at all time periods tested. CONCLUSION: Ceftazidime penetrates into the vitreous cavity of inflamed eyes after intravenous administration and achieves concentrations above the MIC for Pseudomonas organisms. Penetration is greatest in aphakic, vitrectomized eyes.

Animals↗
PubMed1995

Percutaneous cholecystolithotomy: risks, benefits, and long-term outcome.

BACKGROUND: For symptomatic patients with gallbladder stones and a patent cystic duct who wish to retain their 'functioning' gallbladders, percutaneous cholecystolithotomy (PCCL) offers an alternative to open or laparoscopic cholecystectomy. However, there are few data on the risks and benefits of this approach or on the long-term outcome. METHODS AND RESULTS: In 21 patients with symptomatic calcified gallstones, PCCL was successful (gallstone clearance) in 17 (81%). Four to 62 (median, 35) months after clearance 9 of the 17 remained symptom-free and stone-free, whereas 4 developed biliary sludge at 7, 30, 32, and 35 months, 2 of whom subsequently developed gallstones. In four other patients gallstones recurred without evidence of preceding biliary sludge at 9, 16, 19, and 27 months, corresponding to an actuarial gallstone recurrence rate at 36 months of 53.4 +/- SEM 15.1%, and a combined stone/sludge recurrence rate of 63.4 +/- 13.5%. CONCLUSIONS: PCCL is moderately effective but, because of the frequency of complications and sludge/stone recurrence, is likely to have only a limited residual role in the era of laparoscopic cholecystectomy.

Cholecystostomy↗
PubMed1995

Vancomycin levels after intravitreal injection. Effects of inflammation and surgery.

OBJECTIVE: Vancomycin hydrochloride for intraocular injection is the drug of choice for the treatment of suspected gram-positive endophthalmitis. To study its intraocular pharmacokinetics, we injected vancomycin into the vitreous cavity of phakic, aphakic, and aphakic-vitrectomized rabbit eyes and determined its rate of clearance. Inflamed eyes were compared to control eyes in each group. METHODS: Three groups of eyes were prepared. The eyes in Group 1 were phakic, the eyes in Group 2 had the lens removed, and the eyes in Group 3 had both the lens and central vitreous removed. Each group was subdivided into a control group and a group made inflamed by injection of heat-killed Staphylococcus epidermidis. Vancomycin hydrochloride 1 mg in 0.1 cc of diluent was injected into the midvitreous cavity and samples obtained at 2 or 3, 8, 24, and 48 hours after injection. Vancomycin concentrations were measured and clearance rates were calculated for each of the groups. RESULTS: Vancomycin was cleared substantially faster from aphakic-vitrectomized eyes (half-life 9.0 hours) and aphakic eyes (half-life 8.9 hours) than phakic eyes (half-life 25.1 hours). Inflammation increased the rate of elimination of vancomycin only in the aphakic group. CONCLUSIONS: Clearance of vancomycin from the phakic eye is prolonged compared to that of beta-lactam antibiotics, an important pharmacokinetic advantage in treating endophthalmitis. Its clearance from aphakic-vitrectomized eyes is dramatically faster than from phakic eyes and is similar to that of other antimicrobial agents.

Animals↗
PubMed1995

Intraocular injection of ceftazidime. Effects of inflammation and surgery.

OBJECTIVE: The clearance of ceftazidime from the rabbit vitreous cavity after injection into phakic, aphakic, and aphakic vitrectomized rabbit eyes was assessed and the duration of concentrations above the minimal inhibitory concentrations for target gram-negative bacteria was determined. To determine the effect of inflammation on the intraocular pharmacokinetics of ceftazidime, each anatomic group was subdivided into inflamed and control eyes. METHODS: Ceftazidime (2.25 mg) was into the vitreous cavity of inflamed and control rabbit eyes and its concentration was assayed 2, 8, 24, and 48 hours later. The half-life for each of the anatomic groups was calculated. RESULTS: The half-life of ceftazidime in control phakic eyes was 13.8 hours. In aphakic eyes the half-life was 11.8 hours and in the aphakic vitrectomized eyes the half-life was 4.7 hours. Inflammation slightly shortened the half-life in phakic (10.1 hours) and aphakic (8.7 hours) eyes. The half-life in aphakic vitrectomized inflamed eyes was 5.1 hours. CONCLUSION: Vitrectomy and lensectomy significantly shorten the half-life of ceftazidime after intravitreal injection. Inflammation increases clearance to a small degree in phakic and aphakic eyes.

Animals↗
PubMed1994

A cluster of invasive pneumococcal disease in young children in child care.

OBJECTIVE: To investigate a cluster of invasive pneumococcal disease in children 8 to 26 months of age, using standard microbiological procedures and ribosomal DNA gene-restriction patterns to characterize the outbreak strain. DESIGN: Outbreak investigation. SETTING: A family child-care home with six children in Baltimore, Md. RESULTS: During an 8-day period, three of the six children in the family child-care home had febrile illnesses with pneumococcal bacteremia, and a fourth had purulent pneumococcal conjunctivitis. Type 12F Streptococcus pneumoniae was isolated from the four ill children and from the nasopharynges of the two healthy children. Ribotyping revealed all outbreak isolates had an identical ribotype pattern. Administration of rifampin to the children did not eradicate carriage of the organism. CONCLUSIONS: Our data demonstrate that child care provides an opportunity for outbreak of invasive pneumococcal disease in young children. This observation suggests a need for increased alertness for clusters of pneumococcal disease in young children in child-care facilities and underscores the necessity for a pneumococcal vaccine that is effective in infants and young children.

Bacteremia↗
PubMed1994

The design of a case register for tuberculosis. A pilot study in the south-western Cape.

The development and piloting of a tuberculosis register that aims at providing a single source of information for the surveillance of tuberculosis and the measures for its control are discussed. Old-fashioned punch cards are appropriate in both isolated rural and sophisticated urban settings. The card system proved an effective and efficient clinic-based epidemiological tool but its implementation on a broad scale depends on the rationalisation of current administrative procedures.

Forms and Records Control↗
PubMed1993

Progressive deterioration of muscles in mdx mice induced by overload.

1. Extensor digitorum longus muscles of C57 BL/10 and mdx mice were overloaded by removing the synergist tibialis anterior muscle of 9-12-day-old animals. The effect of this operation on the weight, contractile properties and force of the extensor digitorum longus muscle was examined at two different ages, i.e. at 2-3 months (young group) and at 5-8 months (old group). The changes with age in both the control and overloaded muscles of normal and mdx mice are also described. The values obtained from the overloaded muscles were always compared with those for the control, unoperated extensor digitorum longus. 2. In the normal strain of mice the weight of the overloaded extensor digitorum longus muscle in the younger group was increased and it remained higher in the older animals. In the mdx mice the overloaded extensor digitorum longus muscles weighed more in the younger animals but not in the older group of mice. 3. The twitch and tetanic tensions of the overloaded muscles were slightly, but not significantly, increased in the younger group of mdx mice, whereas in the older animals there was a significant decrease in both twitch and tetanic tensions. 4. Thus the overloaded muscles from mdx mice progressively deteriorated with age. In both strains of mice the overloaded muscles become less fatigable with time.

Animals↗
PubMed1993

Prevalence of rotavirus on high-risk fomites in day-care facilities.

STUDY OBJECTIVE: The objective of this study was to determine the prevalence of rotavirus contamination on environmental surfaces in day-care environments, using the polymerase chain reaction technique. DESIGN: High-risk fomites were identified in two day-care centers and sampled biweekly during a 6-month study period. Water samples from water-play tables in each center were also collected during the study period. During an infectious disease outbreak, fomites were sampled from the rooms in which the outbreak occurred. Reverse transcriptase/polymerase chain reaction was carried out for viral detection of rotavirus from the fomites, and standard bacteriologic measures were used to detect bacteria in samples from water-play tables. RESULTS: A total of 96 fomite samples were tested for presence of rotavirus from the two centers, of which 18/96 (19%) tested positive for rotavirus. The timing of the positive samples differed between the two centers. In the center that housed infants, a peak of rotavirus-positive fomites coincided with two enteric outbreaks. Rotavirus contamination was found on the telephone receiver, drinking fountain, water-play table, and toilet handles in both centers. Bacteria in large quantities were also identified in water-play table samples. CONCLUSIONS: Moist surfaces including the telephone, water fountains, and water-play tables are common sources of rotavirus contamination within the day-care environment. Until a safe and affordable drug or vaccine against rotavirus is available for general use, avoidance of rotaviral infections is the most effective method for the prevention of rotavirus gastroenteritis.

Baltimore↗