PubMed Health⌕ Search

Biomedical subjects

R D Jackson

Publications and source records attributed to R D Jackson.

At least 19 recordsLinked to original sources
PubMed1996

Longitudinal studies of the duplication form of Charcot-Marie-Tooth polyneuropathy.

This study presents a longitudinal comparison of motor nerve conduction velocities (MCVs) in patients with Charcot-Marie-Tooth type 1A with proven duplication of a segment of chromosome 17p11.2p12. Results were compared for 8 CMT1A duplication patients from one family whose MCV measurements were taken 22 years apart (1967 and 1989). Measurements from a total of seven median motor and five peroneal motor MCVs were compared. Median MCVs showed a slight reduction that averaged 2.2 m/s, and peroneal MCVs showed an average decrease of 3.0 m/s. In addition, mild objective increase in limb weakness was seen in only 1 of 8 patients and subjective symptoms of gradual worsening of leg strength were noted in half the patients over the same period. In this study of a small group of CMT1A patients with proven segmental duplication of chromosome 17p11.2p12, the motor conduction velocities and clinical motor exam did not change significantly over 22 years.

Adolescent↗
PubMed1996

Bone mass and endocrine adaptations to training in spinal cord injured individuals.

To investigate whether exercise training can produce increases in bone mass in spinal cord-injured (SCI) individuals with established disuse osteopenia, nine subjects (age 28.2 years, time since injury 6.0 years, level of injury C5-T7) were recruited for a 9-month training program using functional electrical stimulation cycle ergometry (FES-CE), which produces active muscle contractions in the paralyzed limb. After training, bone mineral density (BMD, by X-ray absorptiometry) increased by 0.047 +/- 0.010 g/cm2 at the lumbar spine; changes in BMD at the femoral neck, distal femur, and proximal tibia were not significant for the group as a whole. In a subset of subjects training at > or = 18 W for at least 3 months (n = 4), BMD increased by 0.095 +/- 0.026 g/cm2 (+18%) at the distal femur. By 6 months of training, a 78% increase in serum osteocalcin was observed, indicating an increase in bone turnover. Urinary calcium and hydroxyproline, indicators of resorptive activity, did not change over the same period. Serum PTH increased 75% over baseline values (from 2.98 +/- 0.15 to 5.22 +/- 0.62 pmol/L) after 6 months' training, with several individual values in hyperparathyroid range; PTH declined toward baseline values by 9 months. These data establish the feasibility of stimulating site-specific increases in bone mass in severely osteopenic bone with muscle contractions independent of weight-bearing for those subjects able to achieve a threshold power output of 18 W with FES-CE. Calcium supplementation from the outset of training in osteopenic individuals may be advisable to prevent training-induced increases in PTH.

Adult↗
PubMed1995

Dental fluorosis and caries prevalence in children residing in communities with different levels of fluoride in the water.

OBJECTIVES: This study investigated the prevalence of dental fluorosis and caries in 7-14-year-old children residing in communities with negligible (NF: 0.2 ppm), optimal (OPF: 1.0 ppm), and four-times optimal (4X OPF: 4.0 ppm) naturally occurring fluoride in their water systems. METHODS: Examinations were performed on 344 children who were lifetime residents of their communities. RESULTS: Whether using the tooth surface index of fluorosis or Dean's index, children examined in the 4X OPF community had the highest prevalence of dental fluorosis. While the severity of fluorosis seen in the OPF and NF communities was mild in appearance, the results indicate that fluorosis does occur in optimally and negligibly fluoridated communities. Compared to the NF community, DMFT and DMFS scores in the OPF community were 9.2 percent and 21.2 percent lower, respectively. CONCLUSIONS: The ingestion of water containing 1 ppm or less fluoride during the time of tooth development may result in dental fluorosis, albeit in its milder forms. However, in these times of numerous products containing fluoride being available, children ingesting water containing 1 ppm fluoride continue to derive caries protection compared to children ingesting water with negligible amounts of fluoride. Thus, the potential for developing a relatively minor unesthetic condition must be weighed against the potential for reducing dental disease.

Adolescent↗
PubMed1995

Rapid fibrinogen determination with the prothrombin time using a potentiophotometer.

The potentiophotometer (PTPH) is a spectrophotometric device that embodies the electrical, analog solution to Beer's Law. The output of the instrument gives, directly and simultaneously, the concentration of the substance being measured. The PTPH has been applied to the manual determination of fibrinogen (FBG) with the same thrombopalstin injection as the prothrombin time (PT). We have now semi-automated and computerized the PTPH to constitute the coagulation instrument named POTENS+. POTENS+ determines the FBG rapidly, within approximately three to twenty seconds after the PT. With POTENS+, precision, linearity and reference range will be given for its FBG method. The accuracy of POTENS+ will be assessed by comparing it with both automated FBG methods on the MLA Electra 1000C Coagulation Timer. Of these two methods, the automated Clauss method is used as the reference method.

Fibrinogen↗
PubMed1995

The clinical effect of dentifrices containing stabilized stannous fluoride on plaque formation and gingivitis--a six-month study with ad libitum brushing.

The effects of stabilized 0.454% stannous fluoride dentifrices on supragingival plaque, gingival inflammation and gingival bleeding were studied in 549 adult male and female subjects who completed a six-month, double blind clinical study. Following an oral prophylaxis, subjects were randomly assigned to brush with one of the following dentifrices: 1) 0.454% SnF2 stabilized with 2.08% sodium gluconate, 2) 0.454% SnF2 stabilized with 4.16% sodium gluconate, 3) an experimental dentifrice, or 4) 0.243% NaF control dentifrice. Follow-up examinations were conducted at 3 and 6 months. Compared to the control dentifrice at 6 months, stannous fluoride dentifrices stabilized with 2.08% or 4.16% sodium gluconate significantly reduced gingivitis by 18.8% and 18.0%, respectively. There were no statistically significant differences between the two stabilized SnF2 groups with respect to their beneficial effects on gingival health. Gingival bleeding was also reduced, relative to the control dentifrice, for both stabilized SnF2 dentifrices. However, these differences were not statistically significant at p=0.05. The stabilized SnF2 dentifrices were not significantly different from the control dentifrice in their effects on supragingival plaque. No significant differences in adverse oral soft tissue effects were observed between the test and control groups. As expected, accumulation of extrinsic tooth stain increased in the stabilized SnF2 groups. However, the difficulty in removing accumulated dental stain was similar between the control and stabilized SnF2 dentifrices. Since use of SnF2 dentifrices has been reported to produce tooth stain, gingivitis examinations were done with and without custom-made tooth covers to evaluate the potential for examiner bias. Comparable gingivitis and gingival bleeding benefits were observed when the evaluations were conducted with or without the tooth covers. Results from this study support that 0.454% stabilized stannous fluoride dentifrices can provide an important adjunct to the prevention and control of gingivitis when used in combination with regular personal oral hygiene procedures and professional care.

Adult↗
PubMed1995

The clinical effect of a stabilized stannous fluoride dentifrice on plaque formation, gingivitis and gingival bleeding: a six-month study.

The effects of a stabilized 0.454% stannous fluoride dentifrice, currently marketed as Crest Gum Care, on supragingival plaque, gingivitis, gingival bleeding and oral soft tissue condition were studied in 328 adult male and female subjects who completed a six-month, double blind clinical study. Following initial examinations, subjects presenting with a minimum of five gingival bleeding sites received a thorough dental prophylaxis and were instructed to brush at least twice a day for three months with a commercially available fluoride dentifrice, packaged in such a way as to blind its identity to the study subjects. This constituted the three-month pre-test period. At the end of this period, subjects were again examined, given a second oral prophylaxis, and randomly assigned to brush with one of the following dentifrices: 1) stabilized 0.454% stannous fluoride, 2) 0.243% sodium fluoride control, or 3) one of three experimental dentifrices. Subjects were instructed to brush their teeth as they normally would, at least twice a day for one minute per brushing. Follow-up examinations after three and six months of dentifrice use evaluated supragingival plaque, gingivitis, gingival bleeding, extrinsic tooth stain and oral soft tissue status. After six months, the stabilized stannous fluoride dentifrice significantly reduced gingivitis and gingival bleeding by 20.5% and 33.4% compared to the sodium fluoride control group. However, the stabilized stannous fluoride dentifrice group was not significantly different from the control dentifrice group with respect to supragingival plaque scores. As expected, accumulation of extrinsic tooth stain was greater in the stabilized stannous fluoride group than the control group. No unexpected nor clinically significant oral soft tissue health effects were associated with the use of the test dentifrices. The results from this clinical study demonstrate that over a six-month period, twice-daily use of a dentifrice containing 0.454% stabilized stannous fluoride significantly reduced gingivitis and gingival bleeding, relative to a 0.243% sodium fluoride control dentifrice.

Adult↗
PubMed1994

Catecholamine response to exercise and training in individuals with spinal cord injury.

It is unknown whether the catecholamine (CAT) response to acute exercise and prolonged training in humans with spinal cord injury (SCI) is similar to that of neurologically intact man. Plasma samples were collected from seven subjects with chronic SCI (level of injury C5-T7) at rest and during voluntary arm-crank ergometry (ACE) before and after 6 months of training with functional electrical stimulation cycle ergometry (FES-CE). Similar plasma collections were made during one FES-CE exercise training session after 6 months of training. Norepinephrine (NE) and epinephrine (EPI) were measured by HPLC. After FES-CE training, resting NE decreased 37% (950 +/- 150 vs 1510 +/- 350 pmol.l-1 pretraining); resting EPI decreased 80% (54 +/- 10 vs 163 +/- 32 pmol.l-1 pretraining) (P < 0.05 by paired t-tests). No significant changes were observed in group means after training for the CAT response to submaximal ACE; however, five of seven subjects exhibited greater increments in plasma NE with ACE after FES-CE training. Acute FES-CE exercise elicited a 55-844% increase in NE, and a 35-350% increase in EPI above resting values with power outputs eliciting heart rates of 90-146 bpm. These data provide evidence for a systemic CAT response in subjects with SCI during acute FES-CE and reduced resting CAT following 6 months of training with FES-CE.

Adult↗
PubMed1994

A semi-micro method for fibrinogen determination essentially unaffected by turbidity.

A semi-micro method (BR BLUE) is presented using Coomassie Brilliant Blue G-250 color reagent for the determination of fibrinogen on potentially turbid specimens. It is compared with the reference Clauss method using the automated MLA Electra 1000C Automatic Coagulation Timer and the semi-automated Mechrolab Clot Timer. Correlation is excellent (r = 0.97). The BR BLUE method is also seen to be reasonably precise and linear.

Adult↗
PubMed1994

Esthetic inlays and onlays.

Advances in adhesive technology offer the dentist the potential to place tooth-reinforcing restorations with more conservative preparations. At the same time, improvements in tooth-colored restorative materials are yielding high levels of durability and esthetics. The combination of these events has led to the development and continued refinement of an entirely new class of restorations for posterior teeth, called esthetic inlays and onlays. This paper summarizes current scientific and clinical opinion regarding this class of dental restorative and presents clinical technique criteria common to all types of esthetic inlays and onlays whether performed directly or indirectly, in resin or in ceramic.

Cementation↗
PubMed1994

A conservative, aesthetic, restorative treatment of a worn dentition.

Advances in adhesive technology and in materials science have combined to provide the dentist with techniques which increased the ability to achieve the ultimate restorative objective: The restoration of diseased or missing tooth structure, including its appearance, without the additional removal of healthy tooth structure. The learning objective of this article is to illustrate, using a case report, how far restorative dentistry, redefined as aesthetic, adhesive, restorative dentistry, has taken us in this endeavor.

Dental Restoration, Permanent↗
PubMed1993

Four-year study of intermittent cyclic etidronate treatment of postmenopausal osteoporosis: three years of blinded therapy followed by one year of open therapy.

PURPOSE: To determine the effect of long-term intermittent cyclic etidronate treatment on spinal bone density and vertebral fracture rates. PATIENTS AND METHODS: Postmenopausal osteoporotic women (n = 423) were randomized initially into a 2-year, double-blind, multicenter study; it was extended to a third year of blinded treatment followed by open-label treatment: 357 patients continued treatment in Year 3 (305 receiving blinded therapy and 52 receiving calcium supplementation) and 277 in Year 4. During Years 1 through 3, patients received double-blind treatment with phosphate (1.0 g) or placebo twice daily for 3 days, etidronate (400 mg) or placebo daily for 14 days, and calcium (500 mg) daily for the remainder of each 91-day treatment cycle. During Year 4, open-label intermittent cyclic etidronate therapy (without preceding phosphate) was administered to all patients. Spinal bone density and vertebral fracture rates were the main outcome measures. RESULTS: During Year 3, etidronate therapy maintained the significant increases in spinal bone mineral density of the first 2 years. Over the 3-year period, proximal femur bone density increased in etidronate-treated patients. Etidronate therapy for 3 years significantly decreased the vertebral fracture rate in patients at higher risk for fracture (low spinal bone density and three or more vertebral fractures at study entry), as compared with nonetidronate treatment (228 versus 412 fractures per 1,000 patient-years, respectively; p < 0.05). After 1 year of open-label treatment, patients previously treated with etidronate maintained bone mass, and vertebral fracture rates in all groups were lower than in any other study period. There were no apparent serious adverse effects. CONCLUSIONS: Three years of intermittent cyclic etidronate therapy produced significant increases in spinal and hip bone density, with a significant reduction in vertebral fracture rates in patients at higher fracture risk. Maintenance of bone mass and low fracture rate were observed when etidronate was continued for an additional year.

Analysis of Variance↗
PubMed1993

Non-weightbearing exercise may increase lumbar spine bone mineral density in healthy postmenopausal women.

Seven postmenopausal women exercised regularly at moderate intensities (60-80% of maximum heart rate) for eight months on bicycle ergometers. Evaluation of bone mineral density by dual photon absorptiometry revealed a significant (P < 0.01) + 3.55 +/- 1.43% (mean +/- SE) increase in lumbar spine density in the exercisers compared with the 2.44 +/- 0.81% decrease noted in seven sedentary controls. No significant difference in change in femoral neck density was noted between the two groups (+2.51 +/- 2.10% v -0.74 +/- 0.72% for exercisers and controls, respectively; P > 0.10). Dietary intake of calcium and vitamin D was similar in both groups, as was previous exposure to estrogen replacement therapy. These data provide evidence of a prospective nature that non-weightbearing exercise may be effective in reversing bone loss in healthy postmenopausal women.

Bicycling↗
PubMed1993

Heterotopic ossification. The utility of osteocalcin in diagnosis and management.

The status of 12 patients after severe traumatic brain injury was investigated to determine the clinical significance of serum osteocalcin levels during the active phase of neurogenic heterotopic ossification. The diagnosis of heterotopic ossification was confirmed on the basis of radiologic findings. The mean interval between the initial injury and diagnosis of heterotopic ossification was 29 weeks. At the time of diagnosis, serum osteocalcin and total alkaline phosphatase levels were determined along with 24-hour urinary calcium and hydroxyproline excretion. The mean serum osteocalcin level was normal at 4.3 ng/ml (normal range 1.6-6.6 ng/ml) in contrast to the elevated mean values for serum alkaline phosphatase (mean = 173 units/liter; normal range 0-105 units/liter) and urinary hydroxyproline concentration (mean = 39.6 mg/24 h; normal range 7-25 mg/24 hr). Only 17% of the subjects demonstrated an elevated serum osteocalcin level, whereas 58% of the patients had an elevated serum alkaline phosphatase level. Urinary calcium excretion and hydroxyproline excretion were elevated in 33% and 70% of subjects, respectively. These data did not reveal a significant correlation between serum osteocalcin and serum alkaline phosphatase, urinary calcium excretion or urinary hydroxyproline at the time of diagnosis or in serial measurements. Therefore, serum osteocalcin is not a valuable adjunct in confirming the diagnosis of neurogenic heterotopic ossification once the diagnosis has been suggested on the basis of clinical findings and it does not appear to play a role in assessing the maturation of heterotopic ossification.

Adolescent↗
PubMed1993

Aesthetic inlays and onlays: a clinical technique update.

Advances in adhesive technology offer the dentist the potential to place tooth-reinforcing restorations with more conservative preparations. At the same time, improvements in tooth-colored restorative materials are yielding high levels of durability and aesthetics. The combination of these events has led to the development of an entirely new class of restorations for posterior teeth, called aesthetic bonded inlays and onlays. The learning objective of this article is to present an updated, simplified, and predictable technique for placing an indirect composite resin inlay or onlay.

Composite Resins↗
PubMed1992

Weight-training effects on bone mineral density in early postmenopausal women.

We tested the hypothesis that weight training would be an effective modality in maintaining or increasing bone mineral density (BMD) at the lumbar spine, femoral neck, and bone mineral content (BMC) at the distal wrist in early postmenopausal women. A total of 17 women completed a 9 month weight-training program, and 9 women served as a control group. Resistance training occurred three times per week using exercises designed to increase muscular strength. Mean change in lumbar BMD in the weight-trained group (1.6 +/- 1.2%, mean +/- SEM) was significantly different from the change in the control group (-3.6 +/- 1.5%, p less than 0.01) over the 9 month period. No significant weight-training effect was detected at the femoral neck or distal wrist site. We conclude that weight training may be a useful exercise modality for maintaining lumbar BMD in early postmenopausal women.

Bone Density↗
PubMed1992

Clinical effects of a 0.12% chlorhexidine rinse as an adjunct to scaling and root planing.

This trial tested the adjunctive effects of a 0.12% chlorhexidine rinse (Peridex) upon gingival healing following scaling and root planing. Assessments were made on reduction in plaque (Pl), gingivitis (GI), pocket depth and gingival bleeding as measures of treatment benefit. All subjects had Class II, III or IV periodontal conditions. Following baseline examinations, subjects received a gross supragingival scaling and polishing. Subjects were separated by sex and periodontal classification, arrayed by GI scores, and randomly assigned to either the chlorhexidine rinse or a placebo rinse. Subjects were instructed to rinse with 1/2 ounce of their assigned products for 30 seconds twice daily. Following two weeks of product use, the clinical examinations were repeated and two randomly selected, opposing contralateral quadrants were scaled and root planed. After two more weeks of product use (week 4), clinical examinations were repeated and the remaining quadrants were scaled and root planed. At week 6, final clinical examinations were conducted. Since half-mouths were treated at different times and exposed to the treatment rinses for different periods, the data were analyzed for the half-mouths independently 2 and 4 weeks after gross scaling, and 2 and 4 weeks after root planing. A total of 94 subjects (47 in each treatment group) completed all phases of the trial. Gingival healing following scaling and root planing in subjects using a chlorhexidine rinse (0.12%) was significantly better than subjects using the placebo rinse as evidenced by less gingivitis (29%), fewer GI bleeding sites (48%) and less plaque (54%).

Analysis of Variance↗
PubMed1991

Chronic use of the calcium channel blocker nifedipine has no significant effect on bone metabolism in men.

Calcium channel blockers have been reported to have such diverse effects on reduction in protein synthesis, diminished incorporation of proline into new collagen, and decreased hormone release in vitro. The chronic affect of the calcium channel blocker nifedipine was examined in vivo to determine the possible impact of pharmacologic calcium channel blockade on bone metabolism. Eleven Caucasian males treated with an average of 40 mg/d nifedipine for an average of three years were compared to 11 control males matched for age, height, weight, activity level, cardiovascular status, and calcium intake. No significant differences between groups were noted in bone mineral density at the lumbar spine (L2-4), proximal femur (femoral neck, Ward's triangle and trochanter), and proximal and distal radius. There were also no significant differences in parameters of bone turnover (alkaline phosphatase, osteocalcin, urine calcium/creatinine, and hydroxyproline/creatinine ratio), or hormones that might affect calcium metabolism and bone (testosterone, PTH, 25(OH) vitamin D, and calcitonin). In summary, chronic nifedipine use in males is not associated with either a beneficial or adverse effect on bone metabolism.

Adult↗