Engineering a concept: the creation of tissue engineering

Tissue engineering is a fashionable phrase and a new concept. This article analyses what is meant by this term and discusses some of the products that may emerge from the translation of this concept into clinical reality.

Gowning: effects on patient satisfaction

BACKGROUND

Given an extensive literature regarding the doctor-patient relationship, it appears curious that gowning status has received so little attention. The present study examined potential effects of gowning as opposed to not gowning patients at the point of presenting problem. Specifically, effects that gowning status might have on patients' trust in their physician, as well as overall duration of clinic visit, were investigated.

METHODS

Patients (N = 1500) were randomly assigned to gown or non-gown status on arrival for clinic visit. Subsequent screening following predetermined guidelines resulted in 895 subjects participating in the study. Fifty-one percent of these patients (n = 455) fully completed the Trust in Physician Scale. Total time data from check-in to checkout, by gowning status, were kept on all patients.

RESULTS

No significant effects for gowning status were found with respect to patients' trust in their physician or duration of clinic visit. There were also no significant interactions between gowning status, patient sex, physician sex, patient age, or patient education. Significant findings were demonstrated whereby younger patients and patients seeing a doctor for the first time reported less trust in their physician.

CONCLUSIONS

There is not sufficient evidence, to date, to suggest that gowning status has a significant impact on the doctor-patient relationship or the duration of clinic visit.

Size and shape really matter: the influence of design on biocompatibility

Biocompatibility is normally equated with the characteristics of degradation and toxicity. However, there are many more ways by which a medical device can affect the host, including the way in which devices distribute stress in the tissues. This in turn implies that the design of the device can be influential in determining the host response.

Ceramics transformed: manipulating crystal structures to toughen bioceramics

Ceramics have tremendous potential as engineering materials for the construction of medical devices but are inhibited by their inherent brittleness. This article discusses how this problem has been addressed by the development of the process of transformation toughening and places this in the broader context of the new generation of "smart" materials.

Paroxetine increases heart rate variability in panic disorder

Panic patients have decreased heart rate variability, a risk factor for sudden cardiac death, and increased rates of cardiac death and stroke. Imipramine has been found to further reduce heart rate variability in panic. This study uses power spectral analysis to compare autonomic components of heart rate variability in 16 unmedicated control subjects and 17 panic patients before and after treatment with paroxetine at 20 mg/day for 4 weeks. Patients had higher predrug reclining and standing sympathetic activity than control subjects. After drug, patients' total sympathetic activity decreased. Predrug patients failed to increase sympathetic activity on orthostasis, lacking the normal baroreflex response found in control subjects. After drug, patients normalized this sympathetic component of the baroreflex response. Before drug, patients' parasympathetic reclining and standing activity did not differ from control subjects, and patients showed the normal orthostatic parasympathetic decrease. After drug, patients' total parasympathetic activity increased, whereas the baroreflex response was preserved. Nine medicated patients had more than a 50% reduction of panic attacks. In view of paroxetine's increase of heart rate variability, potential benefits of selective serotonin reuptake inhibitors in decreasing cardiac mortality in panic disorder are discussed.

The engineering of polysaccharides

Hyaluronan is a widely distributed and very important biological molecule of the polysaccharide family. Many of the functional characteristics of this substance can be retained when hyaluronan is transformed from a water-soluble substance into a structural biomaterial. This article highlights the potential applications of these materials in the regeneration of injured tissue.

Morphological and structural characteristics of the proximal femur in human and rat

Because the ovariectomized rat model of postmenopausal osteoporosis is the most commonly used small animal model to investigate consequences of bone loss on bone structure and strength, or to assess benefits of the various therapeutic strategies to improve bone mass and strength, the attempt was made to compare histoanatomical and structural characteristics of the femoral neck between human and rat models. In addition to different biomechanics, there is a significant difference in gross- and microanatomy of the proximal femur between humans and rats. Percent of the cortical bone component is much higher in rats (72.5%) relative to humans (12.5%). Also, cortical bone at the femoral neck in rats is evenly distributed, whereas in humans there is a considerable difference in the amount of the cortical bone between the superior half of the femoral neck with cortical thickness being only 0.3 mm, and the inferior half of the neck having 6-mm-thick cortex. Humans have far more cancellous bone at the femoral neck (22.7% average) relative to rats (6.8%). In addition, cancellous bone at the femoral neck in humans is unevenly distributed between the bone center and its periphery. Human samples exhibited striking differences in the cancellous bone structure between weight-bearing and tensile trabecular groups exhibiting clear trabecular orientation consisting of plates and rods, and trabeculae around the neutral bone axis with little mechanical activity exhibiting rod-like trabeculae only. Although humans and rats have a periosteum covering the femoral neck, and each lacks the muscular attachment at intracapsular portions of the femoral neck, rats, in contrast to humans, have the ability to quickly adapt cortical thickness and increase inertia to meet mechanical needs via modeling-dependent periosteal apposition.

Income dynamics and adult mortality in the United States, 1972 through 1989

OBJECTIVES

The aim of this study was to examine relationships between income and mortality, focusing on the predictive utility of single-year and multiyear measures of income, the shape of the income gradient in mortality, trends in this gradient over time, the impact of income change on mortality, and the joint effects of income and age, race, and sex on mortality risk.

METHODS

Data were taken from the Panel Study of Income Dynamics for the years 1968 through 1989. Fourteen 10-year panels were constructed in which predictors were measured over the first 5 years and vital status over the subsequent 5 years. The panels were pooled and logistic regression was used in the analysis.

RESULTS

Income level was a strong predictor of mortality, especially for persons under the age of 65 years. Persistent low income was particularly consequential for mortality. Income instability was also important among middle-income individuals. Single-year and multiyear income measures had comparable predictive power. All effects persisted after adjustment for education and initial health status.

CONCLUSIONS

The issues of low income and income instability should be addressed in population health policy.

Infections with Roseomonas gilardii and review of characteristics used for biochemical identification and molecular typing

Roseomonas is a recently described genus of gram-negative coccobacilli formerly designated as "pink-coccoid" groups I through IV by the Centers for Disease Control and Prevention (Atlanta, Ga) because of the organism's characteristic pink colonies. Since 1991 we have isolated Roseomonas from eight patients; in seven from blood cultures and in one from a skin lesion. The seven blood isolates were from patients with clinically significant underlying diseases who had central venous catheters in place; the majority were associated with polymicrobial catheter infections. Additional characteristics of their infections are described. The eight isolates had originally been identified by us as Centers for Disease Control (CDC) pink-coccoid group III. These organisms were re-identified using the criteria of Rihs et al, and all isolates fit most closely with Roseomonas gilardii. Antibiotic profiles were fairly homogeneous showing susceptibility to many antibiotics, but uniform resistance to cefoxitin, ceftazidime, and piperacillin. Attempts to determine whether the isolates were the same strain by pulsed-field gel electrophoresis suggested that 3 of the isolates were similar. Random amplified polymorphic DNA analysis, however, demonstrated that each of the eight isolates was a unique strain.

The "sterile" debate: the effects of radiation sterilization on polymers

All medical devices have to be sterilized, but the process of killing bacteria and other organisms can also have some deleterious effects on the devices themselves. This article discusses the mechanisms by which gamma irradiation can cause polymer damage and the potential consequences of this.

Glaucoma in a captive-bred great horned owl (Bubo virginianus virginianus)

A captive-bred adult great horned owl (Bubo virginianus virginianus) behaved as though it was bilaterally blind. An ophthalmological examination showed that it had an increased intraocular pressure in both eyes and gonioscopy showed an abnormality of the iridocorneal angles. Retinal changes were also observed. Treatment was not attempted and the owl was euthanased. Histopathology confirmed the abnormal iridocorneal angles, but the exact aetiology of the primary glaucoma was not identified.