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Biomedical subjects

D H King

Publications and source records attributed to D H King.

At least 37 records · Page 2Linked to original sources
PubMed1993

Collagen fibers as a temporary scaffold for replacement of ACL in goats.

ACL substitutes made of braided or plied purified collagen fibers and cross-linked with hexamethylenediisocyanate were implanted into a total of 14 adult goats to achieve resorption within 8 to 10 months. Two types of collagen fiber prostheses differing in degree of collagen purification were tested. The implants were harvested 2 to 11 months postimplantation, tested for mechanical strength, and evaluated by morphological methods. In the first group (n = 5), the less purified and less cross-linked collagen fiber ACL implant induced fast connective tissue ingrowth. At 6 months postimplantation, 40 to 60% of the collagen implant was resorbed. No studies on breaking strength were done in this group. In the second group, highly purified and more crosslinked ACL implants were less infiltrated by cells and were resorbed only by 10 to 20%. Still, the breaking strength was decreased to 10% of the original implant strength. In the second group, the fixation of the ACL implant in the bone tunnel with a bone wedge was insufficient (n = 6); however, additional fixation with metal screws was successful (n = 3). We conclude that cross-linked collagen fibers alone cannot be used as a safe ACL substitute as they quickly lose mechanical strength despite limited biodegradation.

Animals↗
PubMed1993

The intramedullary hip screw.

The intramedullary hip screw is a short intramedullary nail with interlocking screws that can be used to treat subtrochanteric and intertrochanteric femur fractures. This nail, which has the biomechanical advantage of being an intramedullary appliance but can be placed percutaneously, is inserted under fluoroscopic control with the patient on a fracture table. Reaming is not usually necessary. In an initial limited series, complication rates are comparable with existing techniques. Possible future concepts and developments are discussed.

Bone Nails↗
PubMed1991

Quickscan: Doppler ultrasound emulation of angiography--its value prior to arteriography in peripheral vascular disease.

The prevalence of peripheral vascular disease demands a quick, reliable, non-invasive technique for initial assessment. We have devised a new method which combines the two physical principles that (1) Doppler shift is proportional to blood velocity and (2) blood velocity is inversely proportional to arterial cross-section with the ability to track probe position using a non-contacting method. An image of the probe track and any arterial narrowing is shown superimposed on an outline of the patient. Pressure measurement, scan and graphics with final report take about 20 minutes. The accuracy of this system in peripheral vascular disease was evaluated. Thirty-one patients underwent quickscan (QS) and arteriography within an average time of 7 days. Abdominal aorta, common iliac-common femoral, superficial femoral and popliteal artery segments were graded independently as normal, significant stenosis (greater than 50% of diameter) or occluded by both techniques. Of 197 segments, QS correctly assessed 106 normal, 22 stenosed and 28 occluded segments. Four equivocal angiographic stenoses were normal on QS and three severe stenoses were graded occlusion. Fifteen segments on angiography and five on QS were not assessed. For the iliac and superficial femoral artery segments, sensitivity and specificity averaged 77% and 86%, respectively, for all grades. Aortic statistics were invalid (only one significant lesion). Six out of eight popliteal occlusions were correctly diagnosed by QS, but no popliteal stenoses were detected out of six shown on arteriography. Low numbers may contribute to this discrepancy but an improved popliteal scanning method may be necessary. We find initial QS an invaluable aid to direct percutaneous angiography and to indicate potential sites for angioplasty.

Adult↗
PubMed1990

Double-blind randomized clinical trial of self-administered podofilox solution versus vehicle in the treatment of genital warts.

PURPOSE: Genital warts are a highly prevalent and chronic sexually transmitted disease for which there is no completely satisfactory therapy. Conventional ablative therapy requires repeated treatment, often for months or years. This study was undertaken to evaluate the safety and efficacy of 0.5% podofilox in patient-administered treatment of penile warts. PATIENTS AND METHODS: Thirty-eight men with penile warts were randomly assigned to double-blind, self-administration of 0.5% podofilox solution or placebo, twice daily for 3 days per week for 4 weeks. Eleven podofilox and 15 placebo recipients with residual warts then received an additional 4 weeks of open-label treatment. RESULTS: By the end of treatment, podofilox recipients had their mean wart number and area reduced to 15.9% and 5.1% of baseline values, compared to 97.4% and 92.9% in the placebo group (p = 0.0001). Local adverse reactions were more common in the podofilox group, but were transient. Complete disappearance of warts was observed in 25 (53.3%) of 45 treatment courses, including open-label treatment. Recurrences of warts after therapy were frequent. Only 21% of patients remained free of warts 2 weeks after completing treatment, and subsequent recurrences were noted in all patients available for long-term follow-up, which is a common limitation of ablative therapy for genital warts. CONCLUSION: Podofilox 0.5% solution is effective in treating penile warts and is well tolerated in a self-administered regimen. Podofilox 0.5% offers potential advantages in safety and cost over podophyllin resin therapy of genital warts.

Adult↗
PubMed1989

Patient-applied podofilox for treatment of genital warts.

In a double-blind trial, 0.5% podofilox (podophyllotoxin) or placebo was applied by patients to their own genital warts in up to four treatment cycles. At some time during the study, 25 of the 56 podofilox treated patients and none of the 53 placebo group were completely wart-free. At the end of the treatment, 73.6% of the original warts in podofilox treated patients were gone compared with only 8.3% of those in the placebo group (mean percentage of total original wart area was reduced by 82.3% compared with 4.2%). 82% of the treated warts in the podofilox group and 13% in the placebo group had resolved at 6 weeks. Recurrence was observed in 34% of the previously resolved warts. Consistent with this rate of recurrence, new warts developed in a third of the subjects in each group at sites remote from the treatment site. There were no systemic adverse reactions, although transient inflammation, erosion, pain, and burning were common.

Administration, Topical↗
PubMed1988

History, pharmacokinetics, and pharmacology of acyclovir.

A screening program for antiviral drugs begun at Burroughs Wellcome in the 1960s resulted in the discovery of acyclovir in 1974. Preclinical investigation brought the drug to clinical trials in 1977 and the first form of the drug (topical) was available to physicians in 1982. Activity of acyclovir is greatest against herpes 1 and herpes 2, less against varicella zoster, still less against Epstein-Barr, and very little against cytomegalovirus. Acyclovir is an antiviral agent only after it is phosphorylated in infected cells by a viral-induced thymidine kinase. Acyclovir monophosphate is phosphorylated to diphosphate and triphosphate forms by cellular enzymes in the infected host cell where the drug is concentrated. Acyclovir triphosphate inactivates viral deoxyribonucleic acid polymerase. Acyclovir incorporation into the growing viral deoxyribonucleic acid chain causes its termination. The antiviral process has relatively little effect on normal, uninfected cells. An important toxic effect of acyclovir is its potential to cause obstructive nephropathy. The drug is excreted primarily by the kidney, which may require smaller doses in patients with decreased kidney function. Oral dosages of acyclovir as recommended for herpes simplex are probably not adequate for varicella zoster infections.

Acyclovir↗
PubMed1987

Management of viral infections in AIDS patients.

Viral infections, predominantly those of the herpes virus family, account for up to 16% of all clinically significant infections in AIDS patients. Acyclovir has provided successful treatment in AIDS patients suffering from severe herpes simplex and herpes zoster virus infections. Preliminary results are presented on newly developed acyclovir analogues. Desciclovir, an oral prodrug of acyclovir which is metabolized to acyclovir in vivo, allows treatment of virus infections per os, where high serum levels are needed, e.g. in Epstein-Barr virus infections. BW B759U, another analogue of acyclovir, has been used for the treatment of life-threatening or sight-threatening cytomegalovirus infections in AIDS patients. More than 80% of the patients treated for retinitis experienced stabilization or clinical improvement. Antiviral efficacy was demonstrated in 73% of the patients. Azidothymidine, a nucleoside analogue of thymidine, has been developed specifically to treat the HIV infection. Its antiviral activity is based on inhibition of reverse transcriptase. Phase I studies have demonstrated that azidothymidine is well tolerated. Its ability to cross the blood brain barrier makes it an attractive candidate for treatment of HIV. Trials to determine efficacy are in progress.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Oral acyclovir in the treatment of acute herpes zoster ophthalmicus.

Seventy-one nonimmunocompromised patients with herpes zoster ophthalmicus, presenting within seven days of onset of characteristic skin eruption, were enrolled in a prospective, longitudinal, randomized, double-masked, placebo-controlled trial with oral acyclovir. In a previous interim report we noted more prompt resolution of dermatomal signs and symptoms with acyclovir treatment. There was also a reduction of viral shedding in acyclovir-treated patients coupled with a trend to greater rate of microdissemination of the virus in placebo-treated patients (Cobo LM, et al. Ophthalmology 1985; 92:1574-83). While further substantiating these findings, we report that a ten-day course of treatment with oral acyclovir (600 mg, five times a day) is well-tolerated and significantly reduces the incidence and severity of the most common complications of herpes zoster ophthalmicus: dendritiform keratopathy, stromal keratitis, and uveitis. While this acyclovir treatment regimen reduces the zoster-related pain during the acute phase of the disease, especially in patients treated within 72 hours of onset of skin lesions, it has no evident effect on either incidence, severity, or duration of post-herpetic neuralgia in the patients studied.

Acute Disease↗
PubMed1985

Mitral and tricuspid valve anular diameter in normal children determined by two-dimensional echocardiography.

To establish normal values for atrioventricular valve anular diameter in children, we measured the diameter of the mitral and tricuspid valve anuli from 2-dimensional echocardiograms in 103 children aged 1 day to 15 years. Measurements of the mitral valve anulus were made from the parasternal long axis and the apical or subcostal 4-chamber views. The tricuspid valve was measured from the subcostal or apical 4-chamber view. Multiple regression analyses were performed comparing valve anular diameter to weight and body surface area and their respective square root, cube root and logarithmic functions. Mitral and tricuspid anular diameter increased in proportion to the logarithm of weight and body surface area. The best predictor of valve anular diameter was a logarithmic function of body surface area with a calculated correlation coefficient ranging from 0.90 to 0.93 for the 3 anular dimensions. Knowledge of the normal atrioventricular valve anular diameter should be useful in planning palliative or corrective surgery in children with congenital heart disease.

Adolescent↗
PubMed1984

Two-dimensional echocardiographic diagnosis of anomalous origin of the right pulmonary artery from the aorta: differentiation from aortopulmonary window.

Utilizing two-dimensional echocardiography, the diagnosis of anomalous origin of the right pulmonary artery from the aorta was made prospectively in a neonate who presented with signs of congestive heart failure. A complete echocardiographic evaluation, including both right parasternal short-axis and suprasternal long-axis scans, permitted differentiation from other defects in aortopulmonary septation.

Aorta↗
PubMed1984

Anaesthetic considerations in the mucopolysaccharidoses.

The anaesthetic problems we have encountered in eight patients with the mucopolysaccharidoses are described and the pathophysiology of this group of clinically progressive inherited diseases is reviewed with emphasis on the aspects of importance to the anaesthetist.

Adolescent↗