Improved gene therapy for spinal muscular atrophy in mice using codon-optimized hSMN1 transgene and hSMN1 gene-derived promotor

Physiological regulation of transgene expression is a major challenge in gene therapy. Onasemnogene abeparvovec (Zolgensma®) is an approved adeno-associated virus (AAV) vector gene therapy for infants with spinal muscular atrophy (SMA), however, adverse events have been observed in both animals and patients following treatment. The construct contains a native human survival motor neuron 1 (hSMN1) transgene driven by a strong, cytomegalovirus enhancer/chicken β-actin (CMVen/CB) promoter providing high, ubiquitous tissue expression of SMN. We developed a second-generation AAV9 gene therapy expressing a codon-optimized hSMN1 transgene driven by a promoter derived from the native hSMN1 gene. This vector restored SMN expression close to physiological levels in the central nervous system and major systemic organs of a severe SMA mouse model. In a head-to-head comparison between the second-generation vector and a benchmark vector, identical in design to onasemnogene abeparvovec, the 2nd-generation vector showed better safety and improved efficacy in SMA mouse model.

Inhibitory Antibodies against PCSK9 Reduce Surface CD36 and Mitigate Diet-Induced Renal Lipotoxicity

Background

PCSK9 modulates the uptake of circulating lipids through a range of receptors, including the low-density lipoprotein receptor (LDLR) and CD36. In the kidney, CD36 is known to contribute to renal injury through pro-inflammatory and -fibrotic pathways. In this study, we sought to investigate the role of PCSK9 in modulating renal lipid accumulation and injury through CD36 using a high fat diet (HFD)-induced murine model.

Methods

The effect of PCSK9 on the expression of CD36 and intracellular accumulation of lipid was examined in cultured renal cells and in the kidneys of male C57BL/6J mice. The effect of these findings was subsequently explored in a model of HFD-induced renal injury in Pcsk9 ^-/- and Pcsk9 ^+/+ littermate control mice on a C57BL/6J background.

Results

In the absence of PCSK9, we observed heightened CD36 expression levels, which increased free fatty acid (FFA) uptake in cultured renal tubular cells. As a result, PCSK9 deficiency was associated with an increase in long-chain saturated FFA-induced ER stress. Consistent with these observations, Pcsk9^-/- mice fed a HFD displayed elevated ER stress, inflammation, fibrosis, and renal injury relative to HFD-fed control mice. In contrast to Pcsk9^-/- mice, pretreatment of WT C57BL/6J mice with evolocumab, an anti-PCSK9 monoclonal antibody (mAb) that binds to and inhibits the function of circulating PCSK9, protected against HFD-induced renal injury in association with reducing cell surface CD36 expression on renal epithelia.

Conclusions

We report that circulating PCSK9 modulates renal lipid uptake in a manner dependent on renal CD36. In the context of increased dietary fat consumption, the absence of circulating PCSK9 may promote renal lipid accumulation and subsequent renal injury. However, although the administration of evolocumab blocks the interaction of PCSK9 with the LDLR, this evolocumab/PCSK9 complex can still bind CD36, thereby protecting against HFD-induced renal lipotoxicity.

Symptomatic endpoint responder rates to BAROSTIM Therapy

Background

Patients with heart failure with reduced ejection fraction (HFrEF) have varying responses to symptomatic endpoints with device-based HF therapies.

Purpose

Evaluate the symptomatic response to baroreflex activation therapy (BAT) at six months.

Methods

In a trial of subjects with NYHA Class II (recently III) or III HFrEF, left ventricular EF≤35%, guideline directed medical HF therapy (GDMT), no indication for cardiac resynchronization therapy, and NT-proBNP<1600 pg/ml, 264 subjects were randomized to BAROSTIM therapy plus GDMT (BAT group) or GDMT alone (Control group). Six-minute hall walk (6MHW), Minnesota Living with HF (QOL) and NYHA Class were analyzed. Clinically relevant responders were defined by 6-month improvement in 6MHW>10%, QOL>5 points or improvement in at least one NYHA class; super responders were defined by 6-month improvement in 6MHW>20%, QOL>10 points or improvement to NYHA class I.

Results

Both clinically relevant and super responders were significantly higher in BAT versus Control subjects for all symptomatic endpoints. In BAT subjects, 72% had clinically relevant improvements in ≥2 endpoints compared to 29% of Control subjects (p<0.001), and 28% of BAT subjects had super responder improvements in ≥2 endpoints versus 10% of Control subjects (p<0.001).

Conclusion

Among subjects with symptomatic HFrEF, treatment with BAT resulted in clinically relevant and super responder rates. The BAT clinically relevant and super responder rates are similar to those seen with CRT, in CRT-indicated patients.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): CVRx, Inc.

Quality of life response to BAROSTIM Therapy

Background

Patients with heart failure with reduced ejection fraction (HFrEF) have poor quality of life as measured by both physical and emotional dimensions.

Purpose

Evaluate the quality of life in subjects with and without baroreflex activation therapy (BAT) at six months.

Methods

In a multicenter randomized trial conducted in subjects with NYHA class II (recently III) or III HFrEF, left ventricular ejection fraction ≤35%, stable optimal guideline directed medical HF therapy (GDMT), no Class 1 indication for cardiac resynchronization therapy (CRT), and NT-proBNP<1600 pg/ml, a total of 264 subjects were randomized to BAROSTIM therapy plus GDMT (BAT group) or GDMT alone (Control group). Quality of life was measured at baseline and six months using the Minnesota Living with HF Questionnaire (MLWHF) and the EuroQol 5-Dimension Long (EQ-5D) tool. From the MLWHF questionnaire, both a physical and an emotional dimension was analyzed using subsets of the 21 questions. From the EQ-5D, the five individual dimensions and the overall health status (0–100, where 100 is best) was analyzed.

Results

Of the 264 randomized subjects, 120 BAT and 125 Control subjects had 6-month quality of life data. As shown in the table, treatment with BAT resulted in significant improvements in quality of life overall, as well as in the specific dimensions of the quality of life questionnaires, compared to the Control subjects.

Conclusion

Among subjects with symptomatic HFrEF, treatment with BAT resulted in significant improvement in quality of life at six months.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): CVRx, Inc.

Morbidity following lower extremity fractures in men with spinal cord injury

The Veterans Affairs Spinal Cord Dysfunction Registry from 2002 to 2007 was reviewed to determine whether men with spinal cord injury (SCI) and lower extremity fractures had an increased risk of complications compared to those without fractures. We determined that fractures are associated with significant consequences, particularly during the first month postfracture.

INTRODUCTION

Despite increasing longevity, patients with SCI have a substantial number of illnesses and comorbid conditions. Lower extremity fractures are frequent events in these patients. However, whether these fractures are associated with any increased risk of complications in SCI is not certain. The purpose of this report was to determine the impact of lower extremity fractures on morbidities in men with SCI.

METHODS

A population-based, nested, case-control (1,027 cases and 1,027 propensity-matched controls) of men enrolled in the Veterans Affairs Spinal Cord Dysfunction Registry from fiscal years 2002 to 2007 was reviewed to determine whether lower extremity fractures were associated with an increased risk for complications.

RESULTS

In propensity score models matched for demographic (age, race) and SCI-related injury factors (level/completeness of SCI), Veterans Affairs-service connection status, and comorbidities, at 1 month following the fracture, there was an increased risk for respiratory infections, pressure ulcers, urinary tract infections, thromboembolic events, depression, and delirium (p ≤ 0.03 for all). Over 12 months, the only complication more common in fracture cases was pressure ulcers (p < 0.01), with an absolute difference of less than 2 % when compared to controls. There was no significant increased risk of cardiac arrhythmias at any time examined following fracture (≥0.12).

CONCLUSIONS

Lower extremity fractures are associated with significant consequences in men with SCI during the first month postfracture, but they do not persist for a long term, except for pressure ulcers. Targeted interventions to prevent complications should be considered following lower extremity fractures in SCI, particularly in the first month following fracture.

Transarterial chemoembolization for HCC in patients with extensive liver transplantation waiting times

The treatment of hepatocellular cancer (HCC) with transarterial chemoembolization (TACE) prior to orthotopic liver transplant (OLT) is of increasing importance due to the rise in HCC incidence and donor shortage. This single-center study examines 28 patients treated with TACE and 7 patients not treated with TACE, with HCC prior to OLT between 1999 and 2008. The overall 1- and 5-year survival of all transplanted patients with HCC was 94% (33 of 35) and 80% (28 of 35). There was no difference in survival (P = .99) between patients who underwent transplantation immediately (median 95 days) and patients who had significantly longer wait times (median 308 days) when treated with TACE. During extensive wait times for OLT, TACE can be used to keep patients with HCC on the waiting list by preventing tumor progression, with similar outcomes compared with those who underwent transplantation immediately.

Patients' perspective on the comprehensive preventive health evaluation in veterans with spinal cord injury

STUDY DESIGN

Survey research methods.

OBJECTIVES

To assess patient satisfaction with the annual comprehensive preventative health evaluation (CPHE) and to determine if the patient's needs were being met.

SETTING

Department of Veterans Affairs National Survey, United States.

METHODS

A total of 853 subjects with spinal cord injuries participated in a mailed survey regarding the annual CPHE. Subjects were asked about satisfaction with the examination, preferences on how the examination is conducted and whether their needs were being met with the examination.

RESULTS

In all, 76% of the subjects that responded to the survey had completed a CPHE within the previous year. Subjects cited getting their medication and supplies refilled and talking to the doctor as the top two reasons for completing the evaluation. Subjects indicated that they would most like to discuss their muscle strength and weakness, bladder care, chronic pain, digestion and bowel care issues, and equipment problems during their evaluation. The majority of subjects (81%) indicated that they were satisfied with the CPHE. Subjects that were satisfied with the CPHE were also more satisfied with other aspects of care as well.

CONCLUSION

The majority of respondents had completed a CPHE within the previous year. Most respondents cite health issues related to the spinal cord injury as areas they would most like to discuss during the evaluation. The majority of subjects were satisfied with the conduct of the CPHE.

Hysterectomy in Veterans Affairs Medical Centers

OBJECTIVE

To examine the indications and surgical morbidity for women veterans who underwent hysterectomies in Department of Veterans Affairs Medical Centers (VAs).

METHODS

Data on hysterectomies performed in VAs from 1991 to 1997 were abstracted from a surgical quality improvement program.

RESULTS

Records of 1722 women who had hysterectomies in VAs over 6 years were examined. Women were predominately white (62%) and their average age was 42.5 years. Operations included abdominal (74%), vaginal (22%), and laparoscopic-assisted (4%) methods. The most common indications for surgery included uterine leiomyomas (31%), abnormal uterine bleeding (14%), and endometriosis (11%). Indications differed by race (P <.01); nonwhite women were most likely to have surgery for leiomyoma (51%), whereas white women had hysterectomies for leiomyomas (19%), abnormal bleeding (15%), endometriosis (13%), and genital prolapse (11%). The mean postoperative stay was significantly longer for abdominal hysterectomies (4.51 days) than either vaginal or laparoscopic-assisted hysterectomies (2.92 and 2.21 days, respectively; P <.001). The overall complication rate within 30 days was 9%, and the most frequent complication was urinary tract infection (3.3%).

CONCLUSION

Women who underwent hysterectomies in VAs had low complication rates, comparable to hysterectomy complication rates in the United States generally.

Effect of exercise on perceived quality of life of individuals with Parkinson's disease

The purpose of this study was to determine if individuals with Parkinson's disease (PD) who completed an 8-week, supervised PoleStriding exercise program would undergo significant improvements in cognitive skills, activities of daily living, motor function, and quality of life. The Unified Parkinson's Disease Rating Scale (UPDRS) and the Parkinson's Disease Questionnaire (PDQ-39) were used to measure functional independence. Six male volunteers (72.7+/-3.7 years of age) performed PoleStriding exercise three times per week for 37+/-3 minutes. Differences in the participants' pre- and post-training scores on the UPDRS and PDQ-39 were analyzed using the Wilcoxin Signed Ranks Test. A statistically significant improvement occurred in the UPDRS (P<0.026) and PDQ-39 (P<0.028) scores following the moderate-intensity exercise intervention. The results of this nonrandomized clinical trial indicate that an 8-week individualized PoleStriding exercise program increases perceived functional independence and quality of life in individuals with PD.

Indications for a home standing program for individuals with spinal cord injury

Additional analyses were conducted on a recently published survey of persons with spinal cord injury (SCI) who used standing mobility devices. Frequency and duration of standing were examined in relation to outcomes using chi square analyses. Respondents (n = 99) who stood 30 minutes or more per day had significantly improved quality of life, fewer bed sores, fewer bladder infections, improved bowel regularity, and improved ability to straighten their legs compared with those who stood less time. Compliance with regular home standing (at least once per week) was high (74%). The data also suggest that individuals with SCI could benefit from standing even if they were to begin several years after injury. The observation of patient benefits and high compliance rates suggest that mobile standing devices should be more strongly considered as a major intervention for relief from secondary medical complications and improvement in overall quality of life of individuals with SCI.

Follow-up assessment of standing mobility device users

The use of standing devices by spinal cord-injured subjects was investigated through a national survey of a sample of individuals who returned their manufacturer's warranty card to two companies. We obtained a 32% response rate (99/310). The majority of respondents were male (87%) with a median age between 41 and 50 years. Seventy-seven percent were paraplegic and 21% were quadriplegic. Forty percent had between 1 and 5 years experience with their device, and 84% of those responding were currently using their standing device. Forty-one percent used their standing device one to six times a week; two-thirds stood between 30 minutes and 1 hour for each use. Less than 10% of subjects experienced any side effects, such as nausea or headaches, from standing. Twenty-one percent of subjects reported being able to empty their bladder more completely. There was also a favorable response by some individuals on the effects of the standing devices on bowel regularity, reduction of urinary tract infections, leg spasticity, and number of bed sores. Finally, 79% of subjects highly recommended use of standing devices to other people with spinal cord injury. The positive responses of individuals using standing devices is a strong recommendation for the assistive technology community to make these devices more available to individuals with spinal cord injury.

Hand infections in the diabetic patient

Between 1984 and 1994, 23 diabetic patients were admitted to a university hospital/Department of Veterans Affairs (DVA) Medical Centre with a primary or secondary diagnosis of hand infection. We also identified 726 patients admitted to all DVA Medical Centres during the years 1989 through 1994 with co-diagnoses of diabetes mellitus and hand infection. Contrary to previously published literature, most diabetic hand infections are non-specific, confined to the soft tissues, and respond to broad spectrum parenteral antibiotic therapy. When surgery is necessary, most patients do not require amputation.

Evaluation of penetrating injuries of the neck: prospective study of 223 patients

The objective of this study was to assess the role of clinical examination, angiography, color flow Doppler imaging, and other diagnostic tests in identifying injuries to the vascular or aerodigestive structures in patients with penetrating injuries to the neck. A prospective study was made of patients with penetrating neck injuries. All patients had a careful physical examination according to a written protocol. Stable patients underwent routine four-vessel angiography and color flow Doppler imaging. Esophagography and endoscopy were performed for proximity injuries. The sensitivity, specificity, and predictive values of physical examination, color flow Doppler studies, and other diagnostic tests were assessed during the evaluation of vascular and aerodigestive tract structures in the neck. Altogether 223 patients were entered in the study. After physical examination 176 patients underwent angiography and 99 of them underwent color flow Doppler imaging. Angiographic abnormalities were seen in 34 patients for an incidence of 19.3%, but only 14 (8.0%) required treatment. Color flow Doppler imaging was performed on 99 patients with a sensitivity of 91.7%, specificity 100%, positive predictive value (PPV) 100%, and negative predictive value (NPV) 99%. These values were all 100% when only injuries requiring treatment were considered. None of the 160 patients without clinical signs of vascular injury had serious vascular trauma requiring treatment (NPV 100%), although angiography in 127 showed 11 vascular lesions not requiring treatment. "Hard" signs on clinical examination (large expanding hematomas, severe active bleeding, shock not responding to fluids, diminished radial pulse, bruit) reliably predicted major vascular trauma requiring treatment. Among 34 of the 223 total patients (15.2%) admitted with "soft" signs, 8 had angiographically detected injuries, but only one required treatment. An esophagogram was performed on 98 patients because of proximity injuries (49 patients) or suspicious clinical signs (49 patients), and two of them showed esophageal perforations. None of the 167 patients without clinical signs of esophageal trauma had an esophageal injury requiring treatment. It was concluded that physical examination is reliable for identifying those patients with penetrating injuries of the neck who require vascular or esophageal diagnostic studies. Color flow Doppler imaging is a dependable alternative to angiography. An algorithm for the initial assessment of neck injuries is suggested.

Care of central venous catheters for total parenteral nutrition

This report summarizes data obtained via a mailed questionnaire from 129 Department of Veterans Affairs (VA) hospitals regarding current practices in the care of central venous catheters (CVCs) used for total parenteral nutrition (TPN). The size of VA hospitals' acute medical-surgical beds ranged from 14 to 1320 (median 168) beds. Over 6000 patients annually received CVCs for TPN. Hospitals reported using triple-lumen catheters most frequently as their CVC for TPN (80.3%). A povidone-iodine scrub was used to prepare the skin for CVC insertion by 72.6% of reporting hospitals. Sixty percent of hospitals used transparent polyurethane dressings. Care of CVCs varied among hospitals. Catheter-related infection and sepsis rates were within the national average, although < 50% of responding hospitals provided data on these outcomes. The results of this survey point to the need for a national standardized database relative to patients receiving TPN via a CVC.

Management options in vertebral artery injuries

The treatment of 22 patients with vertebral artery injuries was reviewed. Only four patients required an emergency operation. Most of the injuries (13 of 22) were successfully managed by observation. Five patients were managed by angiographic embolization which was successful in three. In three patients with an aneurysm and arteriovenous fistula, proximal embolization of the vascular lesion was not adequate and a suboccipital craniectomy was required for distal ligation. Most vertebral artery injuries can safely be managed without an operation, or by angiographic embolization. Surgical intervention should be reserved for patients with severe bleeding or where embolization has failed.

Penetrating injuries of the neck in patients in stable condition. Physical examination, angiography, or color flow Doppler imaging

BACKGROUND

The initial assessment of penetrating injuries of the neck is controversial, with angiography remaining the gold standard for identifying vascular injuries. Recent reports suggest that physical examination might be an accurate way to evaluate these injuries. Color flow Doppler imaging has been used with promising results to assess extremity injuries, but the role of color flow Doppler imaging in neck injuries has not been studied.

OBJECTIVE

To evaluate and compare the roles of physical examination, color flow Doppler imaging, and angiography in the identification and management of penetrating neck injuries.

STUDY DESIGN

A prospective study of patients in stable condition with penetrating injuries of the neck. All study patients were examined according to a written clinical protocol and subsequently underwent angiography and color flow Doppler imaging. The sensitivity and specificity of physical examination and color flow Doppler imaging were compared with those of angiography.

RESULTS

Eighty-two patients fulfilled the criteria for inclusion in the study. Angiography demonstrated vascular lesions in 11 patients (13.4%), but only two (2.4%) of them required treatment. Serious injuries were detected or suspected during physical examination, but six lesions not requiring treatment were missed. When injuries not requiring treatment were excluded, the sensitivity was 100% and the specificity was 91%. With color flow Doppler imaging, 10 of the 11 injuries were identified, for a sensitivity of 91% and a specificity of 98.6%. The sensitivity and specificity were 100% for clinically important lesions.

CONCLUSION

The combination of a careful physical examination and color flow Doppler imaging provides a reliable way to assess penetrating neck trauma and may be a safe alternative to routine contrast angiography.

Human endothelial cells are defective in diabetic vascular disease

Diabetic vascular disease is characterized pathologically by endothelial cell (EC) hyperplasia and basement membrane (BM) thickening. One key question regarding the pathogenesis of diabetic vascular disease is whether the EC or BM or both are primarily defective and responsible for these pathological changes. Previous studies, which took the approach of creating artificial diabetic conditions, have been inconclusive. It is known, however, that the extracellular matrix may be altered by glycosylation as a result of hyperglycemia, thereby altering EC function. To begin to address this question and more closely mimic the situation in vivo, we characterized human diabetic EC harvested from insulin-dependent diabetic mothers (IDDM) at the cellular and molecular levels. Human EC were isolated from both normal and IDDM umbilical cords and cellular functions evaluated using standard assays of attachment (% attached cells), proliferation (cpm/cell), resistance to detachment under shear stress (number of cells remaining attached), and glucose uptake (cpm/2 X 10(4) cells). Gene expression of major BM components (collagen type IV, laminin beta 1, and laminin beta 2) was quantified by Northern analysis. Diabetic EC demonstrated increased proliferation (two- to eightfold compared to normals), were 20-40% less resistant to shear stress and took up glucose 10-15% more slowly than normal EC. Furthermore, Northern analysis showed that the expression of major BM components was increased by an average of 10-18% in diabetic cells compared to normal cells. These results were consistent with in vivo observations and previously published data.(ABSTRACT TRUNCATED AT 250 WORDS)

The utility of color flow Doppler examination in penetrating extremity arterial trauma

Recent reports from our institution have demonstrated the safety of nonoperative management of minimal arterial injuries. The purpose of this pilot study was to evaluate whether color flow Doppler (CFD) examination could detect minimal arterial injuries caused by penetrating extremity trauma. Twelve patients with minimal arterial injuries identified by arteriography were treated nonoperatively. Each also underwent color flow examination. Seven of 12 arteriographic abnormalities were detected by color flow examination. Two intimal injuries (brachial artery, superficial femoral artery (SFA)), one small (1 mm) pseudoaneurysm (popliteal artery), and two minor vessel occlusions (interosseous artery, branch off SFA) were not detected. These preliminary data suggest that color flow scans may be less sensitive than arteriography in the detection of clinically insignificant lesions such as small intimal defects or small vessel occlusions. Despite this, CFD examination was successful in detecting more significant lesions such as pseudoaneurysms, arteriovenous fistulae, and major vessel occlusions. This is relevant since these lesions may require immediate intervention. These findings suggest the possibility that color Doppler sonography may be able to sequentially monitor these lesions to determine if they resolve or progress. If progression is documented they may require surgical correction. Further prospective studies must be performed to assess whether color flow Doppler examination can supplant arteriography in patients at low or intermediate risk for arterial injury following penetrating arterial trauma.

New evidence and new hope concerning endothelial seeding of vascular grafts

Endothelial cell (EC) seeding of prosthetic bypass grafts has been promoted as a method of improving graft patency. However, an efficient and reliable method of seeding vascular prostheses with ECs is lacking due to inefficient harvesting of ECs and poor attachment and proliferation of cells on the prosthetic surfaces. To investigate the effect of a commonly used prosthetic surface on EC attachment and proliferation, we measured the attachment and proliferation of ECs on polytetrafluoroethylene (PTFE) grafts uncoated or coated with gelatin, laminin, fibronectin, collagen type I and/or III, or RGD (arginine-glycine-aspartate)-containing peptide. EC attachment and proliferation were both significantly decreased on the untreated PTFE graft surface. Conversely, coating of PTFE with fibronectin, RGD, laminin, or gelatin significantly (p less than 0.05) improved the attachment of ECs, with the most striking increases occurring with laminin and gelatin. Similarly, all matrix components in this study improved EC proliferation compared with untreated PTFE, with RGD and gelatin producing the most significant improvement. PTFE adversely effects EC attachment and proliferation. These properties can be improved by treating PTFE graft surfaces with extracellular matrix components in relatively low concentrations. Future investigations are needed to determine whether there are combinations and concentrations of matrix components that will optimize these cellular functions on vascular prostheses.

A randomized trial of the cost effectiveness of VA hospital-based home care for the terminally ill

All admissions to a 1,100-bed Department of Veterans Affairs (VA) hospital were screened to identify 171 terminally ill patients with informal caregivers who were then randomly assigned to VA hospital-based team home care (HBHC, N = 85) or customary care (N = 86). Patient functioning, and patient and caregiver morale and satisfaction with care were measured at baseline, one month, and six months. Health services utilization was monitored over the six-month study period and converted to cost. Findings included no differences in patient survival, activities of daily living (ADL), cognitive functioning, or morale, but a significant increase in patient (p = .02) and caregiver (p = .005) satisfaction with care at one month. A substitution effect of HBHC was seen. Those in the experimental group used 5.9 fewer VA hospital days (p = .03), resulting in a $1,639 or 47 percent per capita saving in VA hospital costs (p = .02). As a result, total per capita health care costs, including HBHC, were $769 or 18 percent (n.s.) lower in the HBHC sample, indicating that expansion of VA HBHC to serve terminally ill veterans would increase satisfaction with care at no additional cost.

Voltage-sensing residues in the S4 region of a mammalian K+ channel

The ability of ion-channel proteins to respond to a change of the transmembrane voltage is one of the basic mechanisms underlying electrical excitability of nerve and muscle membranes. The voltage sensor has been postulated to be the fourth putative transmembrane segment (S4) of voltage-activated Na+, Ca2+ and K+ channels. Mutations of positively charged residues within S4 alter gating of Na and Shaker-type K+ channels, but quantitative correlations between the charge or a residue in S4 and the gating valence of the channel have not yet been established. Here, with improved resolution of the voltage dependence of steady-state activation, we present estimates of the equivalent gating valence with sufficient precision to allow quantitative examination of the contribution of individual charged residues to the gating valence of a mammalian non-inactivating K+ channel. We conclude that at least part of the gating charge associated with channel activation is indeed contributed by charged residues within the S4 segment.

A randomized trial of Veterans Administration home care for severely disabled veterans

This randomized study screened hospital admissions to all wards except Psychiatry and Spinal Cord Injured during a 3-year period to identify 233 severely disabled patients (2 impairments on the Katz Index of ADL) and caregivers who were willing to participate in a pretest-multiple posttest trial of the Hines VA Hospital-based Home Care (HBHC) Program. Patient functional status, morale, and satisfaction with care were measured at baseline, 1 month and 6 months post discharge. Caregiver satisfaction and morale were assessed at the same time periods. All health care services used by both groups were tracked over the 6-month period and converted to cost. Findings include improved 1-month satisfaction with care (P = 0.04) and improved 6-month cognitive functioning (P = 0.04) among HBHC patients and improved 1-month (P = 0.04) and 6-month satisfaction with care (P less than 0.01) among their caregivers. A nonsignificant 10% decrease in net cost of care, was found in the treatment group, largely due to lower use of private sector hospital care.

Tumor seeding from percutaneous biliary catheters

Percutaneous transhepatic biliary decompression has been used since 1973 as a preoperative surgical adjunct in patients with obstructive jaundice. Tumor seeding along the catheter tract is an unusual complication but it occurred recently in one of our patients who had preoperative biliary drainage for four days. Four months after his pancreaticoduodenectomy, a 2-cm nodule developed at the catheter exit site. This nodule was a metastatic focus of adenocarcinoma similar to his pancreatic tumor. He died 1 month later and at autopsy was found to have numerous metastases along the catheter tract. A review of the world literature found 17 other patients with this complication. Thirteen of the 18 total patients had catheters placed for palliation, while 5 patients underwent preoperative drainage before definitive procedures, and 4 of these patients had undergone "curative" resections. Nine of the 18 patients had biliary obstruction from cholangiocarcinoma, while seven patients had primary pancreatic carcinoma. Positioning of the catheter tip above the obstructing tumor and maintaining the catheter for only a short duration before operation (mean 8 days for resected patients, range 2 to 16 days) did not protect against catheter-related tumor seeding. Patients with suspected malignant obstruction of the biliary tract who may have resectable tumors should not undergo routine preoperative biliary decompression. If, on exploration, the tumor is found to be unresectable, then a palliative bypass may be performed.