Geriatrics and rehabilitation medicine: common interests, common goals.

Geriatrics and rehabilitation medicine are both fields with roots in antiquity, and they are both objects of renewed interest in modern times. They share a common philosophy: concern for the total needs of the patient. Both fields employ a team approach to patient care. The rehabilitation medicine physician (physiatrist) has an important role in the care of the elderly. Geriatricians and physiatrists should work together for research purposes and to improve the prevention and treatment of illness and disability in the aging population.

Identification of target genes for the Ewing's sarcoma EWS/FLI fusion protein by representational difference analysis.

The EWS/FLI-1 fusion gene results from the 11;22 chromosomal translocation in Ewing's sarcoma. The product of the gene is one of a growing number of structurally altered transcription factors implicated in oncogenesis. We have employed a subtractive cloning strategy of representational difference analysis in conjunction with a model transformation system to identify genes transcribed in response to EWS/FLI. We have characterized eight transcripts that are dependent on EWS/FLI for expression and two transcripts that are repressed in response to EWS/FLI. Three of the former were identified by sequence analysis as stromelysin 1, a murine homolog of cytochrome P-450 F1 and cytokeratin 15. Stromelysin 1 is induced rapidly after expression of EWS/FLI, suggesting that the stromelysin 1 gene may be a direct target gene of EWS/FLI. These results demonstrate that expression of EWS/FLI leads to significant changes in the transcription of specific genes and that these effects are at least partially distinct from those caused by expression of germ line FLI-1. The representational difference analysis technique can potentially be applied to investigate transformation pathways activated by a broad array of genes in different tumor systems.

Abnormal cholesterol metabolism in the Smith-Lemli-Opitz syndrome: report of clinical and biochemical findings in four patients and treatment in one patient.

We report on four patients with the Smith-Lemli-Opitz (SLO) syndrome who appear to have a defect in cholesterol biosynthesis. The initial results of therapy of one of the patients with cholesterol and bile acids to correct her metabolic abnormalities are described. This finding provides a biochemical marker to help in the diagnosis of this syndrome, may provide insight into the pathogenesis of this disorder, and have therapeutic and prenatal diagnostic implications as well.

Defective cholesterol biosynthesis associated with the Smith-Lemli-Opitz syndrome.

BACKGROUND: The Smith-Lemli-Opitz syndrome (frequency, 1:20,000 to 1:40,000) is defined by a constellation of severe birth defects affecting most organ systems. Abnormalities frequently include profound mental retardation, severe failure to thrive, and a high infant-mortality rate. The syndrome has heretofore been diagnosed only from its clinical presentation. METHODS: Using capillary-column gas chromatography-mass spectrometry, we measured the sterol composition of plasma, erythrocytes, lens, cultured fibroblasts, and feces from five children with the syndrome (three girls and two boys). RESULTS: Plasma cholesterol levels were abnormally low (8 to 101 mg per deciliter [0.20 to 2.60 mmol per liter]) in every patient, being well below the 5th percentile for age- and sex-matched controls. Concentrations of the cholesterol precursor 7-dehydrocholesterol (cholesta-5,7-dien-3 beta-ol), which was not detectable in most of our controls, were elevated (11 to 31 mg per deciliter) more than 2000-fold above normal and were similar to the levels of cholesterol in all tissues from all patients. An isomeric dehydrocholesterol with a structure similar to that of 7-dehydrocholesterol was also detected. CONCLUSIONS: The combination of abnormally low plasma cholesterol levels and a high concentration of the cholesterol precursor 7-dehydrocholesterol points to a major block in cholesterol biosynthesis at the step in which the C-7(8) double bond of 7-dehydrocholesterol is reduced, forming cholesterol. The block may be sufficient to deprive an embryo or fetus of cholesterol and prevent normal development, whereas the incorporation of 7-dehydrocholesterol into all membranes may interfere with proper membrane function.

Assessment of patient function after limb-sparing surgery.

Cancer rehabilitation is becoming more of a focus for the field of physiatry due to increased longevity and the side effects of treatment. In order to investigate the rehabilitation needs of patients undergoing limb-sparing procedures, chart analysis was conducted on 17 children treated for primary bone tumors by resection and an expandable endoprosthetic replacement. Each patient underwent a course of postoperative inpatient and outpatient physical therapy and was followed over an average of 2.5 years. Gait training was relatively straightforward and in seven patients required neither orthosis nor ambulatory aid. The other ten patients walked with a knee orthosis, axillary crutches, or both. Until the time came for reoperation to lengthen the implant, a shoe lift of 1in maximum was added to compensate for the limb length discrepancy. These findings compare favorably with the more complex requirements of high proximal amputees with external prostheses, including more difficult gait training and the need for frequent adjustments, as well as prosthetic replacement as the children grow. It is clear that children undergoing limb-sparing surgery have special needs that should be addressed, including early mobilization, gait training, adjustment to repeated brief hospitalizations for lengthening, and continued follow-up to monitor their activity restriction.

A genetic screen to identify variants of bovine pancreatic trypsin inhibitor with altered folding energetics.

A genetic screening procedure has been developed to identify mutant forms of bovine pancreatic trypsin inhibitor (BPTI) that can fold to an active conformation but are inactivated more rapidly than the wild-type protein. Small cultures of Escherichia coli containing plasmids with mutagenized BPTI genes were grown in microtiter plates, lysed, and treated with dithiothreitol (DTT). Under these conditions, unfolding and inactivation of the wild-type protein has a half-time of about 10 hours. Variants of BPTI that are inactivated within 1 hour were identified by adding trypsin and a chromogenic substrate. Approximately 11,000 mutagenized clones were screened in this way and 75 clones that produce proteins that can fold but are inactivated by DTT were isolated. The genes coding for 68 "DTT-sensitive" mutant proteins were sequenced, and 25 different single amino acid substitutions at 15 of the 58 residues of the protein were identified. Most of the altered residues are largely buried in the core of the native wild-type structure and are highly conserved among proteins homologous to BPTI. These results indicate that a large fraction of the sequence of the protein contributes to the kinetic stability of the active conformation, but it also appears that substitutions can be tolerated at most sites without completely preventing folding. Because this genetic screen is based on changes in folding energetics, further studies of the isolated mutants are expected to provide information about the roles of the altered residues in folding and unfolding.

Mutational analysis of a protein-folding pathway.

The effects of amino-acid replacements on the disulphide-coupled folding pathway of bovine pancreatic trypsin inhibitor have been examined. Replacements at three sites destabilize the native protein relative to the unfolded state, but have different effects on the relative stabilities of the disulphide-bonded folding intermediates, thus allowing the roles of the altered residues during folding to be distinguished.

Venous plethysmography values in patients with spinal cord injury.

To determine whether venous hemodynamics differ fundamentally between patients with spinal cord injury (SCI) and the abled-bodied population, quantitation of lower extremity venous plethysmography values was performed in 14 SCI patients and ten able-bodied subjects. The control group had an average maximum venous outflow (MVO) of 59.3 +/- 2.75 mL/min/100mL of tissue, mean +/- SE, and an average venous capacitance (VC) of 3.2 +/- 0.13mL/100mL. In contrast, the SCI patients had an average MVO of 32.5 +/- 2.57mL/min/100mL and an average VC of 2.3 +/- 0.17mL/100mL. The differences between the two groups were statistically significant, suggesting that the standard venous function index of plethysmography values used in the general population may not be applicable to the SCI population and that, therefore, a new standard for SCI patients derived from a larger data base should be sought.