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Biomedical subjects

L Ferris

Publications and source records attributed to L Ferris.

At least 19 recordsLinked to original sources
PubMed2004

Albumin-genipin solder for laser tissue repair.

BACKGROUND: Laser tissue soldering (LTS) is an alternative technique to suturing for tissue repair that avoids foreign body reaction and provides immediate sealing of the wound. One of the major drawbacks of LTS, however, is the weak tensile strength of the solder welds when compared to sutures. In this study, a crosslinking agent of low cytotoxicity was investigated for its ability to enhance the bond strength of albumin solders with sheep intestine. STUDY DESIGN/MATERIALS AND METHODS: Solder strips were welded onto rectangular sections of sheep small intestine using a diode laser. The laser delivered in continuous mode a power of 170 +/- 10 mW at lambda = 808 nm, through a multimode optical fiber (core size = 200 microm) to achieve a dose of 10.8 +/- 0.5 J/mg. The solder thickness and surface area were kept constant throughout the experiment (thickness = 0.15 +/- 0.01 mm, area = 12 +/- 1.2 mm2). The solder was composed of 62% bovine serum albumin (BSA), 0.38% genipin, 0.25% indocyanin green dye (IG), and water. Tissue welding was also performed with a BSA solder without genipin, as a control group. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Murine fibroblasts were also cultured in extracted media from heat-denatured genipin solder to assess cell growth inhibition in a 48 hours period. RESULTS: The tensile strength of the genipin solder was doubled that of the BSA solder (0.21 +/- 0.04 N and 0.11 +/- 0.04 N, respectively; P = 10(-15) unpaired t-test, N = 30). Media extracted from crosslinked genipin solder showed negligible toxicity to fibroblast cells under the culture conditions examined here. CONCLUSION: Addition of a chemical crosslinking agent, such as genipin, significantly increased the tensile strength of adhesive-tissue bonds. A proposed mechanism for this enhanced bond strength is the synergistic action of mechanical adhesion with chemical crosslinking by genipin.

Adhesives↗
PubMed2003

A dissection and computer tomograph study of tarsal coalitions in 100 cadaver feet.

Most of the clinical studies report the incidence of tarsal coalitions (TC) as less than 1% but they disregard the asymptomatic coalitions. TC have been associated with degenerative arthritic changes. After X-rays, computer tomography (CT) is the most commonly used diagnostic test in the detection of TC. The aims of our study were to establish the incidence of TC; the association between TC and accessory tarsal bones and between TC and tarsal arthritis; and to assess the sensitivity of CT as a diagnostic tool in TC. We performed spiral CT scans of 100 cadaver feet (mean age at death 77.7+/-10.4), which were subsequently dissected. The dissections identified nine non-osseous TC: two talocalcaneal and seven calcaneonavicular. There was no osseous coalition. Tarsal arthritis was identified in 31 cases. Both talocalcaneal coalitions were associated with arthritis while none of the calcaneonavicular coalitions were associated with tarsal arthritis. The CT diagnosed an osseous talocalcaneal coalition and was suspicious of fibrocartilaginous coalitions in eight cases. There was correlation between dissection and CT in two talocalcaneal coalitions and three calcaneonavicular coalitions thus CT identifying 55.5% of the coalitions. CT did not diagnose four non-osseous coalitions and diagnosed errouresly four possible coalitions. In conclusion our study demonstrated that the incidence of non-osseous TC is higher than previously thought (12.72%). The calcaneonavicular coalitions are the most common single type (9.09%) and they do not seem to be associated with arthritic changes in the tarsal bones. Our CT results suggest that spiral CT has a low sensitivity in the detection of non-osseous coalitions and questions if multislice CT should be used routinely when TC are suspected.

Adult↗
PubMed2001

Surgical anatomy of the sural and superficial fibular nerves with an emphasis on the approach to the lateral malleolus.

The aim of this study was to investigate the risk and to analyse the significance of laceration of the sural and superficial fibular nerves during the surgical approach to the lateral malleolus. The sural and the superficial fibular nerves, and their branches were dissected under x 3 magnifying lenses in 68 embalmed leg-ankle-foot specimens. The specimens were measured, drawn and photographed. In 35% of specimens the superficial fibular nerve branched before piercing the crural fascia, and in all these specimens the medial dorsal cutaneous nerve of the foot was located in the anterior compartment while the intermediate dorsal cutaneous nerve of the foot was located in the lateral compartment. In 35% of specimens the intermediate dorsal cutaneous nerve of the foot was absent or did not innervate any toe. The deep part of the superficial fibular nerve was in contact with the intermuscular septum. Its superficial part was parallel with the lateral malleolus when the nerve pierced the fascia more proximally and oblique to the lateral malleolus when the nerve pierced the fascia distally. In one case the intermediate dorsal cutaneous nerve of the foot was in danger of laceration during a subcutaneous incision to the lateral malleolus. In 7 cases (10%) the sural nerve overlapped or was tangent to the tip of the malleolus. Malleolar nerve branches were identified in 76% of the cases (in 28% from both sources). The sural nerve supplies the lateral 5 dorsal digital nerves in 40% of cases. Our study indicates that during the approach to the lateral malleolus there is a high risk of laceration of malleolar branches from both the sural and the superficial fibular nerves. There is less risk of damage to the main trunk of these nerves, but the 10% chance of laceration of sural nerve at the tip of the malleolus is significant. As the sural nerve supplies the superficial innervation to the lateral half of the foot and toes in 40% of cases, the risk of its laceration is even more important than indicated by the common anatomical teaching.

Ankle Injuries↗
PubMed2001

Men and osteoporosis.

BACKGROUND: While strict criteria have been developed for defining osteoporosis in women (bone mineral density measurements more than 2.5 standard deviations below the mean for young adult normal women, i.e. t-score value < -2.5), there still remains a controversy regarding the definition in men. Spinal fractures occur in 5% and hip fractures in 6% of men older than 50 years. There are significant differences between men and women with respect to the pathogenesis of osteoporosis, underlying medical conditions and postfracture sequelae. OBJECTIVE: To provide an overview of the pathogenesis, diagnosis and prevention of osteoporosis in men. DISCUSSION: Osteoporosis is increasingly recognised. Data from the Dubbo Osteoporosis Epidemiology Study suggests that 30% of men in Australia aged over 60 years will suffer from an osteoporotic fracture. It is estimated that 30-60% of men presenting with spinal fractures will have another illness contributing to their bone loss. Osteoporotic fractures in men are associated with higher morbidity and mortality than in women. Lifestyle changes together with daily calcium supplementation should be implemented and vitamin D3 should be considered in men with osteopenia.

Bone Density↗
PubMed2001

Guidelines for treatment of osteoporosis in men.

BACKGROUND: Osteoporosis is associated with significant morbidity and mortality in men. Published randomised controlled trials assessing the benefits of therapy in men with osteoporosis are limited, but those available need to be used to develop management guidelines. OBJECTIVE: To present evidence based guidelines for the treatment of osteoporosis in men. DISCUSSION: It is estimated that 30-60% of men presenting with spinal fractures have another illness contributing to their bone disease. Therefore assessment and treatment of coexisting medical conditions is a vital part of management of osteoporosis. While primary prevention of fractures remains crucial, treatment to ensure further fractures do not occur is equally important. Alendronate is the treatment of choice for men with osteoporosis and fractures, with cyclical etidronate an appropriate alternative and testosterone replacement therapy is indicated in hypogonadal men presenting with osteoporosis.

Calcitriol↗
PubMed2001

Corticosteroid induced osteoporosis. Guidelines for treatment.

BACKGROUND: Last year, Australian Family Physician published 'Guidelines for Management of Postmenopausal Osteoporosis', which were developed by Osteoporosis Australia. Recently, significant advances in our understanding of the treatment of corticosteroid osteoporosis have occurred. OBJECTIVE: The following guidelines, also developed by Osteoporosis Australia, and supported by the National Asthma Campaign, are to help general practitioners identify those patients at risk of this problem and to provide information about current treatment strategies. DISCUSSION: Corticosteroids are widely used and effective agents for the control of many inflammatory diseases. Corticosteroid osteoporosis is a common problem associated with the long term high dose use of these medications.

Adrenal Cortex Hormones↗
PubMed2000

The carbenoid approach to peptide synthesis.

A different approach to the synthesis of dipeptides is described based on the formation of the NHCHR1CONH-CHR2CO bond by carbenoid N-H insertion, rather than the formation of the peptide bond itself. Thus decomposition of triethyl diazophosphonoacetate catalysed by rhodium(II) acetate in the presence of N-protected amino acid amides 8 gives the phosphonates 9. Subsequent Wadsworth-Emmons reaction of 9 with aldehydes in the presence of DBU gives dehydro dipeptides 10. The reaction has been extended to a simple two-step procedure, without the isolation of the intermediate phosphonate, for conversion of a range of amino acid amides 11 into dehydro dipeptides 12 and to an N-methylamide 11 h, and for conversion of a dipeptide to tripeptide (13-->14). Direct conversion, by using methyl diazophenylacetate, of amino acid amides to phenylglycine-containing dipeptides 19 proceeds in good chemical yield, but with poor diastereoselectivity.

Amides↗
PubMed1999

Biomechanical consequences of plantar fascial release or rupture during gait. Part II: alterations in forefoot loading.

With a model using feet from cadavers, we tested the hypothesis that plantar fascial release or rupture alters the loading environment of the forefoot during the latter half of the stance phase of gait. The model simulated the position and loading environment of the foot at two instants: early in terminal stance immediately after heel-off and late in terminal stance just preceding contralateral heel strike. Eight feet were loaded at both positions by simulated plantar flexor contraction, and the distribution of plantar pressure was measured before and after progressive release of the plantar fascia. Strain in the diaphysis of the second metatarsal was also measured, from which the bending moments and axial force imposed on the metatarsal were calculated. Cutting the medial half of the central plantar fascial band significantly increased peak pressure under the metatarsal heads but had little effect on pressures in other regions of the forefoot or on second metatarsal strain and loading. Dividing the entire central band or completely releasing the plantar fascia from the calcaneus had a much greater effect and caused significant shifts in plantar pressure and force from the toes to beneath the metatarsal heads. These shifts were accompanied by significantly increased strain and bending in the second metatarsal. Complete fasciotomy increased the magnitude of strain in the dorsal aspect of the second metatarsal by more than 80%, suggesting that plantar fascial release or rupture accelerates the accumulation of fatigue damage in these bones. Altered forefoot loading may be a potential complication of plantar fasciotomy.

Adult↗
PubMed1998

Biomechanical consequences of plantar fascial release or rupture during gait: part I--disruptions in longitudinal arch conformation.

To examine whether conformational changes induced by plantar fascial division may progress during gait, we loaded the feet of seven cadavers using an apparatus that simulates the actions of the extrinsic plantarflexors. We measured the effects of plantar fasciotomy at two instants in the terminal-stance phase of gait. Radiographic measurements of height of the arch, base length of the arch, and talo first-metatarsal angle were used to assess contributions to arch support made by the plantar fascia, tibialis posterior, peroneus longus and brevis, and digital flexor muscles. Complete fasciotomy caused significant collapse of the arch in the sagittal plane. Early in terminal stance, at the instant after heel-off, mean height of the arch decreased from 47 to 45 mm. Late in terminal stance, at the instant preceding contralateral heel strike, mean height of the arch decreased from 46 to 43. Effects of division of the central band, though significant, were mild. Medial base length of the arch increased from 163 to 167 mm in the absence of tibialis posterior contraction at late terminal stance. Arch-supporting abilities of the other extrinsic muscles were insignificant.

Adult↗
PubMed1995

Appropriateness of transfusions of red cells, platelets and fresh frozen plasma. An audit in a tertiary care teaching hospital.

OBJECTIVE: To determine how current hospital practice for transfusions of red cells, platelets and fresh frozen plasma conformed with published criteria. DESIGN: Elaboration of criteria for transfusion from a review of the current literature; and analysis of the medical records of patients receiving transfusions of red cells (200), platelets (215), and fresh frozen plasma (260) during defined time periods in 1993. SETTING: A large tertiary care teaching hospital. OUTCOME MEASURES: Inappropriateness rates for transfusion episodes and numbers of individual units of blood products administered. RESULTS: Inappropriateness rates for transfusion episodes and numbers of individual units administered were 16% and 10% for red cells, 13% and 11% for platelets, and 24% and 16% for fresh frozen plasma (31% and 21% when transfusions for thrombotic thrombocytopenic purpura were excluded). Red cells and fresh frozen plasma were used inappropriately most frequently in association with a surgical procedure; for platelets, it was their use for bleeding. In many of the transfusions deemed inappropriate, deficiencies of red cells, platelets and/or coagulation factors were documented, but the degree of deficiency did not meet the stringent appropriateness criteria. Twenty-six transfusions were deemed inappropriate because the indication was not documented in the medical record. CONCLUSIONS: Specific problem areas in which blood product use was inappropriate were identified. Guidelines for transfusion appropriateness, education of hospital staff, and a monitoring system to ensure adherence to the guidelines, are required.

Anemia↗
PubMed1995

Influence of extrinsic plantar flexors on forefoot loading during heel rise.

This investigation studied the effects of simulated plantar flexor muscle activity on forefoot loading using a static cadaver model. Nine cadaver feet were mounted in an apparatus in the heel rise position. Using computer-controlled and pneumatic actuators, forces were simultaneously applied to the tendons of the triceps surae, flexor hallucis longus, flexor digitorum longus, peroneus brevis and longus, and tibialis posterior until 750 N of ground reaction force was achieved, at which time forefoot plantar pressure patterns were captured immediately with a pedobarograph. Second metatarsal bending moments were calculated from strain gauge data collected concurrently. Consecutive loading cycles were performed with sequential elimination of simulated muscle force from each tendon except the Achilles. Loss of simulated flexor hallucis longus activity significantly decreased great toe contact forces and significantly increased forces under the forefoot. Simulated loss of both the flexor hallucis longus and flexor digitorum longus caused significant decreases in contact area, pressure, and force beneath the toes and significant increases in contact area and force under the forefoot. Bending moments in the second metatarsal were shown to vary directly with peak pressure under the second metatarsal head (r = 0.801). These findings demonstrate the load distributing function of the extrinsic plantar flexors during heel rise.

Adult↗
PubMed1995

Strain and loading of the second metatarsal during heel-lift.

Metatarsal stress fractures occur in military recruits after long marches and in athletes after episodes of overtraining involving running or jumping. It has been demonstrated that contraction of the plantar flexors of the toes helps to counteract the moments placed on the metatarsals by body weight. It is possible that physiological fatigue due to strenuous or repetitive exercise reduces the rate and force of contraction of the plantar flexors, thereby increasing metatarsal strain per cycle, and that this mechanism is the primary cause of stress fractures of these bones. To test the hypothesis that fatigue of the plantar flexors causes increased metatarsal loading, thereby predisposing these bones to stress fracture, we measured metatarsal strains in nine fresh cadaveric feet with use of an apparatus that simulated physiological loading due to body weight as well as contraction of the plantar flexors. Each foot was loaded to 750 newtons of ground-reaction force by simulated contraction of the triceps surae, and strains were recorded in the mid-part of the shaft of the second metatarsal. Tests were repeated with use of simulated activity of different combinations of the flexor digitorum longus, flexor hallucis longus, peroneus brevis, peroneus longus, and tibialis posterior muscles. In situ bending moments and axial loads subsequently were derived for each configuration. Dorsal strain was significantly reduced by simulated contraction of the flexor hallucis longus. Plantar-dorsal bending was significantly reduced by simulated contraction of the flexor digitorum longus.

Achilles Tendon↗
PubMed1992

A comparative study of computed tomographic and plain radiographic methods to measure vertebral rotation in adolescent idiopathic scoliosis.

A comparative analysis of two methods of measuring vertebral rotation in adolescent idiopathic scoliosis is reported in this article. Nash and Moe's pedicle shift method (using plain anteroposterior radiographs) is compared with a new method using computed tomographic scans. The computed tomographic scans of the whole length of the major curve and the scout films obtained from seventeen girls aged 12.5-14 years were measured for rotation of each vertebra of the curve (total number of vertebrae measured by two methods = 173). This study has three interesting new findings: 1) Those vertebrae with Nash & Moe grade 0 had up to 11 degrees of vertebral rotation when measured using the computed tomographic method. Therefore, Nash & Moe's grade '0' is not a neutrally rotated vertebra; 2) For Nash & Moe grade 1 and 2, the computed tomographic method revealed statistically significantly greater rotation for lumbar vertebrae than thoracic vertebrae. There was a similar pattern for Nash & Moe grade 0 but these differences were not statistically significant; and 3) Simple formulae are reported to convert Nash & Moe's grades into angle of vertebral rotation as obtained by CT method separately for thoracic and lumbar vertebrae.

Adolescent↗
PubMed1988

Increasing the relevancy and usefulness of programme evaluation: a comprehensive evaluation.

Most organizations implement evaluation research to determine how to improve a programme or to decide if a programme should be continued. However, evaluation research can be used to help organizations make relevant and valid decisions for the cycle of programme planning, programme development, programme implementation, and programme operation. This paper describes a "comprehensive evaluation model" which will provide a framework for understanding the importance of evaluation activities at all programme phases (i.e. planning, development, implementation, and operation). Four sequential evaluation stages are presented as being the framework for the "comprehensive evaluation model". It is argued that these stages are essential to the organization and the evaluator in helping them adequately provide an assessment of a programme's efficiency and effectiveness.

Evaluation Studies as Topic↗
PubMed1981

Arterial plasma histamine levels at rest, and during and after exercise in patients with asthma: effects of terbutaline aerosol.

Eight asthmatic patients and two normal subjects performed two identical exercise tests 140 minutes apart (first test preceded by inhalation of saline and the second by terbutaline sulphate). A ninth asthmatic patient exercised twice after placebo 40 minutes apart. Arterial plasma levels of histamine and cyclic AMP, expiratory flow rates and volumes were measured at rest and during and after exercise. After the first test the mean +/- SEM fall in PEFR was 45.2 +/- 2.6%. In five asthmatics there was an increase in plasma histamine (mean +/- SEM 14.8 +/- 3.3 pmol ml-1) coinciding with exercise-induced asthma (EIA). Histamine levels returned to pre-exercise values within 30 minutes. After terbutaline these five patients had histamine levels greater than those observed before, during, or after the first test. This effect may have been the result of changes in pulmonary microcirculation. After the second test the levels decreased indicating no further release of histamine in response to exercise. No EIA occurred in these patients after terbutaline. The other patients and the two normal subjects had little or no change in histamine throughout the study. The one patient in whom exercise was repeated after placebo demonstrated less histamine release and less EIA after the second test.

Adult↗