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Biomedical subjects

R H Johnson

Publications and source records attributed to R H Johnson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Efficacy of a sonic toothbrush on inflammation and probing depth in adult periodontitis.

This single-blind, 8-week study compared the efficacy of a sonic toothbrush and a manual brush in 40 patients with adult periodontitis. Qualitative clinical indices and quantitative laboratory methods were used to monitor the periodontal status of 3 pockets 5 to 7 mm deep in each subject. Patients were randomly assigned either a sonic or manual toothbrush. The two groups were comparable with respect to age, gender, and anatomical location of the test sites. Data were collected from all sites at baseline and at 2, 4, and 8 weeks. Over the 8-week period, both groups showed significant improvements in the clinical indices used. Descriptive statistics indicated the sonic brush group had greater improvement than the manual group in the clinical parameters (gingival index, bleeding index, probing depth, and clinical attachment level). Gingival crevicular fluid (GCF) flow was significantly lower in the sonic brush group (P = 0.018). Considerable variation was present in the levels detected for both inflammatory cytokines tested, however, concentration of interleukin-1 beta was significantly lower in the GCF of sonic group patients (P = 0.05), while concentration of interleukin-6 was significantly reduced in both groups (P < or = 0.05) (t tests). Under these conditions, there is some evidence to suggest that the sonic toothbrush is more beneficial in resolving inflammation in patients with moderate periodontal disease.

Adolescent↗
PubMed1995

Cone-beam CT for radiotherapy applications.

Clinical implementation of cone-beam tomography has been hampered by the lack of two-dimensional electronic x-ray detectors that can encompass the full width of the body. We encountered the undersized detector problem in our development of a cone-beam CT system for radiotherapy applications. In order to mitigate the problem, we developed an algorithm which permits an increased reconstruction volume to be imaged using a detector of a given size. We describe the algorithm and report on its implementation using a radiotherapy simulator configured with a digital fluorography unit.

Algorithms↗
PubMed1994

Peritoneal fluid lactic acid and diagnostic dilemmas in acute abdominal disease.

Our previous canine research suggested that the determination of peritoneal fluid lactic acid levels may be helpful in the evaluation of potential acute abdomen cases. To investigate the clinical significance of those findings, we obtained simultaneous peritoneal and plasma lactic acid values from patients undergoing emergency celiotomy or in whom surgical consultation was sought to rule out an acute abdomen. The lactic acid value was significantly higher in peritoneal fluid than in plasma in patients who were found to have hollow viscus perforation, gangrenous intestine, peritonitis, or intra-abdominal abscess. In contrast, the values were similar in patients who did not have those conditions. Our findings suggest that the calculated difference between simultaneous peritoneal and plasma lactic acid values is a helpful diagnostic index for patients in whom the diagnosis of acute abdomen is not otherwise obvious.

Abdomen, Acute↗
PubMed1994

Treatment of severe pneumonia in hospitalized patients: results of a multicenter, randomized, double-blind trial comparing intravenous ciprofloxacin with imipenem-cilastatin. The Severe Pneumonia Study Group.

Intravenously administered ciprofloxacin was compared with imipenem for the treatment of severe pneumonia. In this prospective, randomized, double-blind, multicenter trial, which included an intent-to-treat analysis, a total of 405 patients with severe pneumonia were enrolled. The mean APACHE II score was 17.6, 79% of the patients required mechanical ventilation, and 78% had nosocomial pneumonia. A subgroup of 205 patients (98 ciprofloxacin-treated patients and 107 imipenem-treated patients) were evaluable for the major efficacy endpoints. Patients were randomized to receive intravenous treatment with either ciprofloxacin (400 mg every 8 h) or imipenem (1,000 mg every 8 h), and doses were adjusted for renal function. The primary and secondary efficacy endpoints were bacteriological and clinical responses at 3 to 7 days after completion of therapy. Ciprofloxacin-treated patients had a higher bacteriological eradication rate than did imipenem-treated patients (69 versus 59%; 95% confidence interval of -0.6%, 26.2%; P = 0.069) and also a significantly higher clinical response rate (69 versus 56%; 95% confidence interval of 3.5%, 28.5%; P = 0.021). The greatest difference between ciprofloxacin and imipenem was in eradication of members of the family Enterobacteriaceae (93 versus 65%; P = 0.009). Stepwise logistic regression analysis demonstrated the following factors to be associated with bacteriological eradication: absence of Pseudomonas aeruginosa (P < 0.01), higher weight (P < 0.01), a low APACHE II score (P = 0.03), and treatment with ciprofloxacin (P = 0.04). When P. aeruginosa was recovered from initial respiratory tract cultures, failure to achieve bacteriological eradication and development of resistance during therapy were common in both treatment groups (67 and 33% for ciprofloxacin and 59 and 53% for imipenem, respectively). Seizures were observed more frequently with imipenem than with ciprofloxacin (6 versus 1%; P = 0.028). These results demonstrate that in patients with severe pneumonia, monotherapy with ciprofloxacin is at least equivalent to monotherapy with imipenem in terms of bacteriological eradication and clinical response. For both treatment groups, the presence of P. aeruginosa had a negative impact on treatment success. Seizures were more common with imipenem than with ciprofloxacin. Monotherapy for severe pneumonia is a safe and effective initial strategy but may need to be modified if P. aeruginosa is suspected or recovered from patients.

Adult↗
PubMed1994

Effects of antibiotic treatment on clinical conditions with guided tissue regeneration: one-year results.

The one-year results of a regenerative procedure in patients treated with or without antibiotics are presented. Expanded polytetrafluoroethylene (ePTFE) was placed over mandibular molar Class II furcation invasions and retained for four weeks. The patients in group 1 received no antibiotics; patients in group 2 received amoxicillin/clavulanate potassium during the first 10 post-operative days. The initial differences in tested microorganisms and post-surgical inflammation indicated that the use of the antibiotic might enhance the long-term outcome. After one year, the reduction in mean probing depth of the furcation invasions was 2.0 +/- 1.2 mm for group 1 and 1.8 +/- 1.1 mm for group 2. An overall gain of 0.8 mm of clinical attachment was found. Twenty-two of the 24 sites were re-entered. Wide individual variations were found but the changes between pre-treatment and one-year data for any of 6 linear measurements of hard tissue landmarks did not differ between groups or between pre-treatment and re-entry. A combination of an overall loss of 0.4 mm alveolar bone at the crest and 0.3 mm gain of bone at the bottom of the furcation defects was found. Volumetric analysis indicated an average 32% bone fill for both groups, ranging from a decrease in defect volume by 84% (gain) to an increase of the size of the furcation invasion by 66% (loss). A decrease in defect volume > 30% was found at 7 sites from each group. The antibiotic may have controlled initial inflammation, but 12 months later it had no direct effect on bone regeneration or soft tissue attachment.

Alveolar Bone Loss↗
PubMed1994

Health visitors' use of health education material.

An Oxford study reveals wide variations in health visitors' use of printed health education materials with clients. Their choice appears dictated largely by personal preference and judgement, and by lack of availability of suitable materials. MARY DIXON and RALPH JOHNSON argue that standards and guidelines are needed on which, how and why such leaflets are used.

Community Health Nursing↗
PubMed1993

Invasive sinusitis with intracranial extension caused by Curvularia lunata.

Curvularia lunata has previously been linked to localized sinus infection in immunocompetent hosts. We treated a case of pansinusitis with extensive bone destruction and intracranial extension caused by C lunata. Curvularia lunata was identified when typical fungal macroconidia appeared on culture. Numerous surgical procedures, in addition to a 12-month course of antifungal therapy consisting of 4 g of intravenous amphotericin B and an 8-month course of 400 mg of oral ketoconazole daily, were required to control the infection. This unusual case of invasive sinusitis caused by C lunata alerts the treating physician to the presence of this mold and gives an overview of diagnostic method as well as the management.

Combined Modality Therapy↗
PubMed1993

Value of preoperative bone and liver scans and alkaline phosphatase in the evaluation of breast cancer patients.

We reviewed the results of 133 bone scans and 63 liver scans (computed tomography, liver-spleen radionuclide scan, or ultrasonography) obtained for the preoperative evaluation of breast cancer patients. Information on the preoperative staging of breast cancer (TNM classification) was available in 131 of 133 patients. Bone scans had a low preoperative yield as only 4 of 133 patients (3%) had a positive bone scan that correlated with the results of plain films. Only 1 of 63 patients had a liver scan suggestive of possible metastasis. We also found that the alkaline phosphatase level was not a good predictor of bone or liver metastases in breast cancer patients. In 103 patients with normal bone scans, the majority (54%) had elevated alkaline phosphatase levels; conversely, 9 of 30 patients (30%) with abnormal scans had normal alkaline phosphatase levels. Furthermore, 51 of 63 patients (81%) with elevated alkaline phosphatase levels had normal liver scans. Approximately $74,000 was spent on these liver and bone scans.

Alkaline Phosphatase↗
PubMed1993

Effect of frequency and conductivity on field penetration of electromagnetic hyperthermia applicators.

The field penetration of electromagnetic hyperthermia applicators in 2.5-29 g l-1 saline (NaCl) solutions over a range of frequencies is investigated. Calculated field penetration based on the current-element method agrees well with measurement at frequencies above about 100 MHz, but at lower frequencies measured field penetration becomes progressively less than calculated as conductivity is reduced. Experimental results and finite-difference time-domain (FDTD) method modelling show that the electromagnetic field produces circulating currents. The effect of these circulating currents on the heating pattern of the applicators should be considered when planning hyperthermia treatment.

Electromagnetic Fields↗
PubMed1993

Effects of antibiotic treatment on clinical conditions and bacterial growth with guided tissue regeneration.

Mucogingival flaps were reflected over pairs of mandibular molar teeth with Class II furcation invasions. The dimensions of the furcations were measured. The teeth were debrided and an expanded polytetrafluoroethylene (e-PTFE) membrane was placed and retained over one furcation of each pair (test site) for 4 weeks. The second site served as a control. Eight patients (group 1) with 12 e-PTFE sites received no antibiotic. Seven patients (group 2) with 12 e-PTFE sites were administered amoxicillin/clavulanate potassium for 10 days. Paper-points were used to collect bacterial samples and clinical indices were recorded at baseline and weekly for 4 weeks. Paper-point samples and the e-PTFE collected at week 4 were sonicated and analyzed by DNA probes for seven putative pathogens. At baseline no parameter showed statistical differences between groups or sites. At week 1 significantly greater levels of Prevotella intermedia type I (P < 0.05) and Fusobacterium nucleatum (P < 0.01) were found in group 1. At week 4, paper-point samples from test sites (P < 0.05) and e-PTFE materials (P < 0.001) showed significantly higher presence of Bacteroides forsythus in group 1. No significant microbial changes were found for control sites over time or between groups. The total bacterial load at test sites over time increased similarly for patients administered or not administered the antibiotic. Clinical signs of inflammation were significantly greater in group 1 and associated with the presence of B. forsythus (P < 0.01).

Adult↗
PubMed1992

Autonomic responses to carbohydrate ingestion and head-up tilt in elderly subjects with orthostatic hypotension.

To investigate the role of glucose and insulin in the development of hypotension following glucose ingestion in elderly subjects with orthostatic hypotension, the autonomic responses to glucose and xylose ingestion were studied in five elderly subjects with age related orthostatic hypotension (without autonomic failure), five elderly control subjects and three elderly subjects with evidence of autonomic failure. Heart rate, blood pressure, plasma noradrenaline and plasma arginine vasopressin responses to glucose ingestion and to xylose ingestion were investigated. All subjects were supine for 90 min following ingestion of each carbohydrate and were then tilted 45 degrees head-up for 10 min. Blood pressure was maintained in elderly control subjects following ingestion of both carbohydrates and during tilting. The elderly group with orthostatic hypotension, while supine had a fall in systolic blood pressure 60-90 min following both glucose and xylose ingestion. Diastolic blood pressure was lowered 60-90 min after glucose but not xylose. During tilting, blood pressure fell by similar levels following both carbohydrate ingestions; plasma noradrenaline levels after 2 min and plasma arginine vasopressin levels after 10 min tilting were significantly less following glucose ingestion compared to xylose ingestion. The autonomic failure group while supine had a fall in systolic blood pressure 60-90 min following both glucose and xylose ingestion. Diastolic blood pressure was lowered 60-90 min after glucose but not xylose. During tilting, blood pressure fell by similar levels following both carbohydrate ingestion. Plasma noradrenaline and arginine vasopressin levels were unchanged after ingestion of either carbohydrate, and during tilting.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Autonomic involvement in systemic diseases.

It is now well recognized that autonomic dysfunction may occur in disorders affecting the various body systems. Over the past year important observations have been reported in congestive cardiac failure, reflex sympathetic dystrophy (RSD), acquired immune deficiency syndrome (AIDS) and diabetes mellitus.

Autonomic Nervous System↗
PubMed1991

A new set of calibration standards for estimating the fat and mineral content of vertebrae via dual energy QCT.

A new set of calibration standards has been developed for implementing a dual-energy (DE) quantitative CT technique for estimating the fat and bone content of vertebrae. The QCT technique is based upon a three-component model of bone and utilizes calibration materials that mimic those components in their X-ray attenuation properties. The three components we chose to simulate are bone (mineral plus collagen), fat and a fat-free red marrow. This choice was predicated upon our desire to employ materials that would facilitate later experimental verification of the method. The calibration standards and a set of test samples were manufactured of tissue-simulating epoxy resins. They were employed in studies of the accuracy (consistency) and precision of the technique and in a study of 21 normal postmenopausal women. Estimates of the bone and fat content of the test samples were consistent with the manufacturer's specifications to within 13 mg/ml and 7 vol%, respectively. Long-term reproducibility (coefficient of variation) for both quantities was about 3%. The average bone content of the T12-L3 vertebrae of the human subjects was 262 +/- 32 mg/ml (152 +/- 18 mg/ml calcium hydroxyapatite or mineral) and the average fat content was 63 +/- 8%. Conventional single energy (SE) QCT measurements of these vertebrae were about 23% less than the DE mineral measurements, which is consistent with the differences between SEQCT and ash content that others have determined via chemical analysis. The DE fat content is, in absolute terms, about 15% greater than values reported in the literature and may be due to an error in the assumed composition of red marrow. The true accuracy of the bone and fat estimates is to be determined in a planned human vertebral specimen study.

Bone Density↗
PubMed1991

The identification of female sandflies of the subgenus Larroussius by the morphology of the spermathecal ducts.

The complete spermathecae of 13 species of Larroussius were dissected and examined. The base of the duct of 4 species (aculeatus, guggisbergi, tobbi, wui) is bell-shaped: they are easily distinguished by differences in shape. Five other species (perniciosus, pedifer, longicuspis, perfiliewi, galilaeus) have lateral structures at the base of the duct: slight differences between perniciosus, pedifer and longicuspis distinguish these species: the structures of perfiliewi and galilaeus are the same. Species of a third group (neglectus, syriacus) have a common duct with no lateral structures: they are distinguishable by minor differences. Two species (ariasi, orientalis) from a fourth group with expanded distal parts of the duct; the size and shape of the expanded parts easily separates the species. The study shows a great variation in the morphology of the base of the spermathecal ducts of Larroussius and confirms the value of this feature in identifying otherwise indistinguishable females of the subgenus.

Animals↗