The paradox of sympathetic vasoconstriction in exercising skeletal muscle.

Is there sympathetic vasoconstriction in exercising skeletal muscle? Although convincing evidence exists that demonstrates vasoconstriction in active muscle, the proposition that the sympathetic nervous system constricts skeletal muscle during exercise poses a paradox, given the robust vasodilation that occurs in muscle during exercise. Ultimately, muscle perfusion is a balance between metabolic vasodilation and sympathetic vasoconstriction.

Pregnancy and post partum: changes in cognition and mood.

Steroidal hormones are increasingly recognized as highly relevant in multiple aspects of brain functioning. While basic science has actively worked to advance understanding of fundamental steroid mechanisms within the brain, investigation of the neurobehavioral outcomes of reproductive hormone actions on the human brain has received less attention. We argue that the dramatic steroidal hormone changes seen in human reproduction must be systematically studied and may provide novel explanations of cognitive and mood disorders associated with reproductive events.

Gender-related cognitive deficits in Alzheimer's disease.

Recent studies have identified cognitive deficits in semantic memory and verbal language abilities among women with Alzheimer's disease (AD). Few studies to date have explored gender differences in episodic memory function in AD. The present study compared the performance of men and women diagnosed with AD on a battery of neuropsychological measures.

Psychological factors and hyperemesis gravidarum.

Hyperemesis gravidarum (HG) is a condition of severe, intractable nausea and vomiting during pregnancy. It has long been held that HG is a psychosomatic illness reflective of a long-term psychological trait, that is, conversion disorder. We investigated this possibility by conducting a two-phase study: (1) a comparison of women with (n = 9) and without (n = 10) HG during pregnancy and (2) a comparison of nonpregnant women who did (n = 10) and did not (n = 12) have HG during their most recent pregnancies.

Focal osteolysis at the junctions of a modular stainless-steel femoral intramedullary nail.

Background: During routine follow-up of patients treated with a three-piece stainless-steel modular femoral nail, osteolysis and periosteal reaction around the modular junctions of some of the nails were noted on radiographs. The purpose of this study was to evaluate the prevalence, etiology, and clinical relevance of these radiographic findings.

Methods: Forty-four femoral fractures or nonunions in forty-two patients were treated with a modular stainless-steel femoral intramedullary nail.

The increasing need for nonoperative treatment of patients with osteoarthritis.

Osteoarthritis affects more patients than almost any other musculoskeletal disorder. The number of patients suffering joint pain and stiffness as a result of this disease will increase rapidly in the next decade. Although operative treatments of patients with osteoarthritis will continue to improve and the number of operative procedures will increase slightly in the next decade, only a small fraction of the patients with osteoarthritis will require operative procedures.

Telomere erosion and senescence in human articular cartilage chondrocytes.

Aging and the degeneration of articular cartilage in osteoarthritis are distinct processes, but a strong association exists between age and the incidence and prevalence of osteoarthritis. We hypothesized that this association is due to in vivo replicative senescence, which causes age-related declines in the ability of chondrocytes to maintain articular cartilage. For this hypothesis to be tested, senescence-associated markers were measured in human articular chondrocytes from donors ranging in age from 1 to 87 years.

Exercise attenuates alpha-adrenergic-receptor responsiveness in skeletal muscle vasculature.

Attenuation of sympathetic vasoconstriction (sympatholysis) in working muscles during dynamic exercise is controversial. A potential mechanism is a reduction in alpha-adrenergic-receptor responsiveness. The purpose of this study was to examine alpha(1)- and alpha(2)-adrenergic-receptor-mediated vasoconstriction in resting and exercising skeletal muscle using intra-arterial infusions of selective agonists.

Parasympathetic innervation of canine tracheal smooth muscle.

To investigate whether efferent parasympathetic fibers to the tracheal smooth muscle course through the pararecurrent nerve rather than the recurrent or the superior laryngeal nerve, we stimulated all three nerves in anesthetized dogs. We also recorded the pararecurrent nerve activity response to bronchoconstrictor stimuli and compared it with pressure changes inside a saline-filled cuff of an endotracheal tube. Electrical stimulation (30 s, 100 Hz, 0.

Argument against use of food additives for osteoarthritis of the hip.

Food additives and other forms of alternative medicines have been embraced by the general public. Some of these compounds including glucosamine and chondroitin sulfate have shown efficacy in relieving pain associated with osteoarthritis. However, evidence is limited concerning the chondroprotective ability of these agents.

Dynamic exercise attenuates sympathetic responsiveness of canine vascular smooth muscle.

The phenomenon of reduced responsiveness of the skeletal muscle arterial vasculature to sympathetic activation during exercise (sympatholysis) remains controversial. The purpose of this study was to examine the vascular effects of sympathoactivation in dynamically exercising skeletal muscle. Mongrel dogs (19-24 kg) were instrumented chronically with transit-time ultrasonic flow probes on the external iliac arteries.

Tenascin-C in tendon regions subjected to compression.

Tendon regions subjected almost exclusively to tension differ from regions subjected to high levels of compression as well as tension. Regions not exposed to compression consist primarily of spindle-shaped fibroblasts surrounded by densely packed longitudinally oriented collagen fibrils formed principally from type-I collagen. In contrast, regions subjected to compression have a fibrocartilagenous structure and composition: they consist of spherical cells surrounded by a matrix containing hyaline cartilage proteoglycans (aggrecan) and type-II collagen as well as type-I collagen.

Osteoarthritis: new insights. Part 1: the disease and its risk factors.

Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors (such as genetics, dietary intake, estrogen use, and bone density) and of local biomechanical factors (such as muscle weakness, obesity, and joint laxity).

Diabetic muscle infarction.

Diabetic muscle infarction is a rare complication of diabetes mellitus that is not clearly defined in the orthopaedic literature. This study is a descriptive case series of 7 new cases of diabetic muscle infarction and 55 previously reported cases in the literature. In the majority of patients, diabetic muscle infarction presents as a localized, exquisitely painful swelling and limited range of motion of the lower extremity.

Damage control mechanisms in articular cartilage: the role of the insulin-like growth factor I axis.

Articular chondrocytes maintain cartilage throughout life by replacing lost or damaged matrix with freshly synthesized material. Synthesis activity is regulated, rapidly increasing to well above basal levels in response to cartilage injury. Such responses suggest that synthesis activity is linked to the rate of matrix loss by endogenous "damage control" mechanisms.

Anosognosia and Alzheimer's disease: the role of depressive symptoms in mediating impaired insight.

The relation between anosognosia and dementia severity in Alzheimer's disease (AD) has been unclear. We constructed a measure that quantified the difference between the perceptions of deficits of patients with AD (n = 23) and ratings from a knowledgeable informant as a measure of anosognosia. There was no correlation between dementia severity and anosognosia.

The role of chondrocyte-matrix interactions in maintaining and repairing articular cartilage.

Throughout life chondrocytes maintain the articular cartilage matrix by replacing degraded macromolecules and respond to focal cartilage injury or degeneration by increasing local synthesis activity. These observations suggest that mechanisms exist within articular cartilage that stimulate chondrocyte anabolic activity in response to matrix degradation or damage. An important cartilage anabolic factor, insulin-like growth factor I (IGF-I), appears to have a role in stimulating chondrocyte anabolic activity.

Development and validation of the Parental Intrusiveness Rating Scale among bulimic and comparison women.

Objective: Based on hypotheses generated during clinical interviews with 80 women with a lifetime history of bulimia nervosa (BN), we designed an instrument for assessing the extent to which women with BN report parental intrusiveness and breakdown of appropriate role boundaries during their adolescent development.

Method: Through an iterative process of item generation and scale administration, the Parental Intrusiveness Rating Scale (PIRS), consisting of 20 maternal items and 20 paternal items, was developed. Maternal subscales include Invasion of Privacy, Jealousy and Competition, and Overconcern with the Daughter's Eating, Weight, and Shape.

The variable presentation and natural history of Langerhans cell histiocytosis.

Langerhans cell histiocytosis is not a well defined or predictable disease. Instead, it is a spectrum of disorders of unknown etiology that vary widely in presentation and natural history, but have in common the proliferation of histiocytic cells and infiltration of these cells into normal tissues. Although the lesions of Langerhans cell histiocytosis consist primarily of histiocytes, eosinophils are a prominent feature in some lesions.

Osteoporosis: the increasing role of the orthopaedist.

Osteoporosis is an ever-increasing problem as our population ages. However, it is also to a large extent a preventable problem. The orthopaedist now has the ability to determine bone mass, the rate of turnover, and the fracture risk.

Synovial joint degeneration and the syndrome of osteoarthritis.

The adverse effects of osteoarthritis on the quality of life for tens of millions of people and on the costs of health care and economic productivity make it a major health problem that will increase in incidence and impact with the aging of the population. Although in most patients the cause of osteoarthritis remains unknown and no cure has been identified, appropriate diagnosis and treatment, including education of the patients, can minimize symptoms and help patients maintain active and productive lives. Accomplishing this aim requires that physicians have an understanding of the pathophysiology of joint degeneration and the relationships between joint degeneration and the clinical syndrome of osteoarthritis.