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Biomedical subjects

G B Holmes

Publications and source records attributed to G B Holmes.

At least 19 recordsLinked to original sources
PubMed1994

Fractures and dislocations of the foot and ankle in diabetics associated with Charcot joint changes.

This study was undertaken to evaluate the occurrence of Charcot joint changes in diabetic patients after fractures and/or dislocations of the foot and ankle. There were 20 fracture/dislocations of the foot and ankle in 18 patients, with an average follow-up of 27 months (range 14-70 months). There were eight fractures of the midfoot, six fractures of the ankle, four fractures of the hindfoot, and two fractures of the forefoot. Eight fractures were followed by the development of Charcot changes: five in the midfoot and one each in the forefoot, hindfoot, and ankle. Of nine fractures recognized early and initially treated by early immobilization or ORIF, seven healed uneventfully. Two fractures, both open injuries, developed soft tissue infection and osteomyelitis, respectively. Of the 11 fractures in which there was a delay in diagnosis and treatment, eight developed Charcot changes. The early recognition and appropriate treatment of fractures in diabetic patients appears to be important in the prevention of Charcot joint changes.

Adult↗
PubMed1994

Treatment of delayed unions and nonunions of the proximal fifth metatarsal with pulsed electromagnetic fields.

Nine delayed unions and nonunion of the proximal fifth metatarsal were treated with pulsed electromagnetic fields (PEMF). All fractures healed in a mean time of 4 months (range 2-8 months). Those fractures treated with both pulsed electromagnetic fields and a nonweightbearing cast healed in a mean time of 3 months (range 2-4 months). The average duration of follow-up was 39 months (range 24-60 months). There were no refractures. When compared with reported healing times and morbidity for conventional casting, medullary curettage with inlay bone, and closed axial intramedullary screw fixation, pulsed electromagnetic fields provided an effective alternative for the treatment of delayed unions and nonunion of the proximal fifth metatarsal.

Adult↗
PubMed1992

Possible epidemiological factors associated with rupture of the posterior tibial tendon.

Rupture of the posterior tibial tendon has been postulated to occur, in part, as a result of degenerative changes to the tendon. This possibility was examined by a review of 67 patients (average age 57 years) diagnosed with rupture of the posterior tibial tendon. Forty-five of the 67 patients (60%) had one or more of the following positive medical histories: (1) hypertension, (2) obesity, (3) diabetes mellitus, (4) previous surgery or trauma about the medial aspect of the foot, or (5) steroid exposure. Thirty-five patients (52%) had either hypertension, diabetes mellitus, or obesity. A statistical correlation was demonstrated between rupture of the posterior tibial tendon and obesity (P = .005) and to a lesser extent hypertension (P = .025). These disorders have been uniformly associated with an acceleration of the degenerative processes associated with aging, commonly via an acceleration of microvascular and macrovascular diseases. An additional vascular risk is implicated by the known zone of hypovascularity of the posterior tibial tendon and risk of rupture secondary to systemic or local injections of corticosteroids. The prevalence of posterior tibial tendon rupture parallels the degenerative processes of aging, hypertension, diabetes mellitus, and obesity. Additionally, the effects of corticosteroids and local surgical procedures may further be associated with local vascular impairment and eventual rupture.

Adult↗
PubMed1992

The effects of wearing high heeled shoes on pedal pressure in women.

The purpose of this study was to investigate the effects of increased heel height in women's shoes on foot pressure during walking. An increase in heel height increased the maximum peak pressure under the metatarsal heads in the forefoot, decreased the time to maximum peak pressure under the metatarsal heads, and increased the rate of loading to the metatarsals during early support. The higher pressures noted with increased heel height were accompanied by a more uniform distribution of pressure beneath the forefoot. These findings may denote increased stress to the various tissues in the foot when walking in high heeled shoes, which may contribute to deleterious orthopaedic changes. Quantitative studies need to be conducted to determine whether orthopaedic changes occur with prolonged wearing of high heeled shoes.

Adult↗
PubMed1992

Fractures of the talar neck. A mechanical study of fixation.

Anatomical reduction and rigid internal fixation of fractures of the talar neck allow early mobilization of the ankle and subtalar joints. Forty fresh tali from cadavera were fractured across the talar neck and were internally fixed with one of four methods. The specimens were again loaded to failure, and mean yield loads, yield deformations, stiffness, and energy absorbed were compared. The two configurations of screws that were inserted posterior to anterior provided yield loads superior to those of screws inserted anterior to posterior. All combinations of screws were stronger than Kirschner wires. Comparisons of yield deformations, stiffness, and energy absorbed corroborated these results. The calculated theoretical maximum shear force across the talar neck during active motion was 1129 newtons. This exceeded the strength that was provided by Kirschner wires and anteriorly inserted screws but not that provided by screws that were placed posteriorly.

Adolescent↗
PubMed1992

Bioequivalence of verapamil hydrochloride extended-release pellet-filled capsules when opened and sprinkled on food and when swallowed intact.

A study was performed to determine whether verapamil hydrochloride administered in extended-release pellet-filled capsules is bioequivalent to the same formulation administered by sprinkling the contents of the capsules onto food. Thirty-two healthy subjects participated in the randomized, two-way crossover study. In treatment A, the subjects swallowed the contents of a verapamil hydrochloride extended-release pellet-filled capsule, 240 mg, that had been sprinkled on applesauce. In treatment B, the subjects swallowed the same type of capsule intact. Blood samples were drawn at baseline, every hour for 10 hours, and at 12, 15, 24, 30, 36, and 48 hours after each dose administration. The plasma was analyzed for verapamil and norverapamil by high-performance liquid chromatography. The following calculations were performed: AUC0-48, AUC0-infinity, Cmax, tmax, and k. Results for the two treatments were compared by analysis of variance. There were no significant differences between the AUC0-48, AUC0-infinity, Cmax, tmax, and k for the two methods of dose administration. For verapamil the differences for all variables were less than 5%, and for norverapamil the differences were less than 4% for all variables except tmax (9.5%). The 90% confidence intervals were within acceptable limits for all variables except the norverapamil tmax comparison. Sprinkling the contents of extended-release pellet-filled capsules onto food provides verapamil hydrochloride that is bioequivalent to that obtained from the intact capsules.

Administration, Oral↗
PubMed1991

Surgical management of foot disorders: bunions and bunionettes.

Pathologic conditions of the metatarsophalangeal joints comprise the majority of painful conditions of the forefoot. Clinical manifestations commonly include hallux valgus (bunion), bunionette ("tailor's bunion"), and metatarsalgia. Conservative treatment remains the hallmark of initial management of these disorders. Conservative measures emphasize the adequate accommodation of the forefoot within the toe box of the shoe and the even distribution of plantar pressures by various metatarsal pads or bars and soft insoles. Numerous and sometimes controversial surgical procedures have been developed when conservative measures fail to achieve significant pain relief. In general, these procedures can be grouped as 1) soft tissue realignment procedures, 2) bony realignment procedures, 3) combined bony and soft tissue realignment procedures (ie, osteotomy), 4) bony and joint resection, 5) arthrodesis techniques, and 6) Silastic joint replacement techniques.

Foot Diseases↗
PubMed1991

Practical considerations for the use of the pedobarograph.

The pedobarograph functions as a device for the dynamic, quantitative measurement of pedal pressures. To date, little attention has been paid to various practical questions concerning its operation. For example, the number and timing of trials sufficient to provide meaningful information upon which to reliably base investigational or management decisions has yet to be addressed. Twenty volunteers were used for the measurement of pedal pressures for 15 trials during three separate sessions. Statistical analysis for the determination of MIVQUE(0) estimates and maximum likelihood estimates were used to determine the individual variability, the variability of the specific area of the foot, the daily variability, and the trial-to-trial variability. This analysis indicated that for the assessment of pedal pressures in a clinical setting, the variance factors were sufficiently minimized by obtaining multiple measurements. The improvement in the estimate of error by obtaining trials on different days was overshadowed by the potential benefit of doing extra trials on a single day. Three trials on 1 day should sufficiently reduce estimates of error for both clinical and investigational purposes.

Adult↗
PubMed1991

Chronic rupture of the Achilles tendon: a new technique of repair.

A new operative technique is described for the treatment of patients who have a rupture of the Achilles tendon. The large gap between the proximal and distal stumps of the Achilles tendon in seven patients was bridged by use of the tendon of the flexor digitorum longus as the graft. At the most recent follow-up examination (average follow-up, thirty-nine months; range, two to six years), the result was excellent or good in six patients and fair in one. Postoperatively, two patients needed an adjuvant procedure: one, a local rotation flap and the other, a split-thickness skin graft. Both patients had excellent restoration of function. The patient who had a fair result had a persistent limp and residual discomfort. There were no re-ruptures.

Achilles Tendon↗
PubMed1990

A quantitative assessment of the effect of metatarsal pads on plantar pressures.

The treatment of metatarsalgia secondary to the plantar prominence of the metatarsal heads has lead to the development of numerous orthotic devices designed to decrease pressures in these areas. In spite of the considerable cost of some of these devices, there has yet to be much objective evidence of their efficacy. This study assessed the effect of a simple metatarsal pad on pressures transmitted to the metatarsal heads. Quantitative measurements of dynamic peak pressures for 10 asymptomatic subjects with and without metatarsal pads were made using the pedobarograph. Female volunteers had a reduction in peak metatarsal pressures from 12% to 60% when a small metatarsal pad was appropriately applied to the foot. In two of five males there was a decrease in metatarsal pressure of 14% to 44%. One male had no change in pressure, while two others had an increase in pressure from 8% to 28%. When properly positioned and appropriately monitored, metatarsal pads can be an inexpensive and effective means of reducing metatarsal pressures.

Adult↗
PubMed1989

Absorption of valproic acid suppositories in human volunteers.

The absorption of valproic acid administered by rectal suppository was studied in six male volunteers. Valproic acid was incorporated into a synthetic lipid base in our pharmacy. Each subject received 500 mg of valproic acid by rectal suppository and 500 mg of oral valproate sodium syrup one week apart; 13 blood samples were drawn to determine serum concentrations over 48 hours after administration of each formulation. Significant differences were evident in the amount absorbed, maximum serum concentration, and time to achieve maximum serum concentration between the oral and rectal formulations. Mean absorption after rectal suppository was 80%. Maximum serum concentration was 43.4 mg/L after oral administration and 29.2 mg/L after rectal suppository. The time to achieve maximum serum concentration was 1.0 hour after oral syrup and 3.1 hours after rectal suppository. Absorption of the rectal suppository was consistent and complete within 3 hours. The use of valproate sodium in rectal suppository form can be a more convenient and satisfactory method of administering valproic acid when the oral route is impossible. Dosage increases may be necessary, and serum concentrations should be monitored.

Administration, Oral↗
PubMed1989

Pharmacokinetics of felbamate, a novel antiepileptic drug: application of mixed-effect modeling to clinical trials.

Felbamate is a novel antiepileptic drug currently undergoing clinical trials in the United States. Serum felbamate concentration data from a phase II safety and efficacy trial were analyzed using NONMEM. A one-compartment, open model with first-order absorption and elimination was used. Body weight, sex, concurrent folic acid therapy, and phenytoin dose and dose:concentration ratio did not affect the estimates for felbamate clearance (Cl). Carbamazepine dose and dose:concentration ratio (CDCR) led to significant improvements in the objective function. The final models for felbamate clearance and volume of distribution (Vd) were as follows: Cl(L/hr) = 2.43 + 0.429*CDCR/240, Vd (L) = 51. The coefficient of variation of clearance was only about 12%, which may be indicative of the highly selective patient population. The clearance estimates are similar to those obtained in healthy volunteers and in patients receiving lower dosages of felbamate. The volume of distribution estimate, however, is slightly smaller than that reported previously. Valuable pharmacokinetic information can be obtained from the routine monitoring of serum concentrations during safety and efficacy trials.

Adolescent↗
PubMed1988

Compliant populations: variability in serum concentrations.

Safety and efficacy studies of new antiepileptic drugs require strict adherence to prescribed dosage regimens. Therefore, they provide a unique opportunity to investigate the variability in serum concentrations that are seen in a compliant group of motivated patients. Phenytoin and carbamazepine serum concentrations from two safety and efficacy trials were evaluated for coefficient of variation, difference from baseline concentration, and percent difference. Coefficient of variation for phenytoin was usually less than 20% and was not influenced by baseline serum concentration or frequency of administration. There was no relationship between serum concentration and frequency of administration on carbamazepine coefficient of variation which was less than 25% in most cases. Most PHT differences from baseline were within 5 micrograms/ml, whereas most CBZ differences were within 2 micrograms/ml. Most PHT concentrations were within 30% of each other whereas most CBZ concentrations were within 40% of each other. Data from this study provide information regarding the variability of phenytoin and carbamazepine concentrations under ideal conditions and can be used to set limits for fluctuations of concomitant antiepileptic drugs in safety and efficacy trials or ideal patient care settings.

Anticonvulsants↗
PubMed1988

Failure of the metal-backed patellar component after total knee replacement.

Twenty-five patients had failure of a metal-backed patellar component after total knee replacement. Five manufacturers and seven designs were involved. There was no apparent correlation between failure of the component and the age or sex of the patient, the diagnosis, the use of cement, the femorotibial alignment, or the use of lateral release. The patients in whom the patellar implant failed were relatively heavy, and the diagnosis in most of them was osteoarthritis. The failure was due to one of two mechanisms: wear or fracture, or both, of the polyethylene over the edge of the metal backing (eighteen components), or dissociation of the polyethylene or the base-plate, or both, from the anchoring pegs (seven components). In many of the patients, failure of the component was not suspected before arthrotomy. The failure led to considerable wear of the femoral component in eleven patients and to metal-induced synovitis in twenty-three. We concluded that metal backing may predispose the patellar component to a small but important likelihood of failure, and we urge caution in choosing a metal-backed patellar implant. Additional research is necessary to improve designs for the patellar component, especially if metal backing is to be used.

Aged↗
PubMedDate not supplied

Quantitative determination of phenytoin and phenobarbital in capillary blood by Ames Seralyzer.

We evaluated the use of serum obtained from capillary blood specimens with the Seralyzer ARIS (AMES Division Miles Laboratories) assay for phenytoin (PHT) and phenobarbital (PB). The Ames Seralyzer method is capable of measuring PHT and PB concentrations in 10 microliter of serum. Therefore, it may be used to measure concentrations of these drugs in small blood samples, such as obtained by skin puncture and capillary tube collection. In this study, simultaneous venous and capillary samples were obtained from 90 patients with epilepsy. Seralyzer results were compared with serum values from venous blood determined with a gas chromatographic (GC) method. Comparison of PHT values obtained by Seralyzer (Ys) versus GC by linear regression gave the equation: Ys = 0.36 + 0.88 X (r2 = 0.93, n = 63). The mean difference between the Seralyzer and GC was -0.96 micrograms/ml (p less than 0.001). For PB, the equation was: Ys = -0.53 + 1.07 X (r2 = 0.93, n = 31) with a mean difference of +1.28 micrograms/ml (p = 0.02).

Adolescent↗