Dietary vitamin K influences intra-individual variability in anticoagulant response to warfarin

The relationship between dietary intake of vitamin K, fat, plasma vitamin K concentrations and anticoagulation response to warfarin within individuals, as well as the contribution of dietary vitamin K to differences in warfarin dose requirements between individuals were investigated in 53 patients on warfarin therapy who had stably controlled anticoagulation. Each patient completed a dietary record of all foods consumed on a daily basis for 4 weeks. Each week a blood sample was taken for measurement of the international normalized ratio (INR), plasma vitamin K, triglycerides and warfarin enantiomer concentrations. The patients' genotype for CYP2C9 was also determined. Regression analysis of the data showed that, for each increase of 100 microg in the daily dietary intake of vitamin K averaged over 4 d, the INR was reduced by 0.2. There was no correlation between warfarin daily dose and average daily dietary vitamin K intake when calculated over 28 d. The regression model for warfarin dose showed that, while dietary vitamin K had no effect, CYP2C9 genotype (P = 2%) and age (P < 1%) significantly contributed to inter-patient variability in warfarin dose requirements. A consistent intake of vitamin K could reduce intrapatient variability in anticoagulation response and thus improve the safety of warfarin therapy.

Pharmacological activities of crude acetone extract and purified constituents of Salvia moorcraftiana Wall

The crude acetone extract of aerial parts of Salvia moorcraftiana Wall. was screened for various biological activities including Lemna bioassay, antifungal, antibacterial, leishmanicidal, insecticidal activities and brine shrimp cytotoxicity. It was found to possess strong phytotoxic activity against Lemna aequinoctials Welve. and moderate antifungal activity against animal and plant pathogens. The purified chemical constituents were tested for enzyme inhibition activity. Two constituents (compounds 3 and 8) were found to be effective inhibitors of alpha-glucosidase.

Constituents of Salvia moorcroftiana

A new aromatic ester, 3-oxodecan-1-o1 p-hydroxybenzoate (1) was isolated from Salvia moorcroftiana aerial parts along with four other constituents.

Application of fiberoptic sensors for the study of hepatic dysoxia in swine hemorrhagic shock

OBJECTIVES

To determine whether the simultaneous measurement of tissue pH, Pco2, and Po2 with a multiple-parameter fiberoptic sensor can be used to indicate the onset of hepatic dysoxia, to determine critical values, and to assess their use in predicting negative outcomes.

DESIGN

Prospective animal study.

SETTING

University research laboratory.

SUBJECTS

Fourteen Yorkshire swine.

INTERVENTIONS

Hemorrhagic shock (n = 11) was induced over 15 mins to lower systolic blood pressure to 40 mm Hg and was maintained for 30, 60, or 90 mins. Resuscitation was achieved with shed blood and warm saline to maintain mean pressure >60 mm Hg for 120 mins. Sham animals (n = 3) were subjected to 90 mins of sham shock, followed by a 120-min recovery period.

MEASUREMENTS AND MAIN RESULTS

The multiple-parameter sensor continuously measured tissue pH, Pco2, and Po2. pH and Pco2, indicators of anaerobic metabolism, were plotted against tissue Po2. All shocked animals, but no sham animals, showed a biphasic relationship between Po2 and both pH and Pco2. Curves were fit to both an exponential and a dual-line linear function to determine critical values for Po2, pH, and Pco2. The length of time the animal was dysoxic was evaluated as a predictor of negative outcome. Critical values determined from the exponential models were more sensitive indicators of negative outcome than values determined from the linear model and more sensitive than arterial lactate and tonometric intramucosal pH and Pco2.

CONCLUSIONS

The multiple-parameter sensor offers the unique opportunity to study solid as well as hollow organ dysoxia through the simultaneous measurement of interstitial pH, Pco2, and Po2 in a small tissue region. The gradual transition from sufficient oxygen availability to dysoxia as a result of hemorrhage was better described by an exponential equation. The length of time that pH was below or Pco2 was above the critical value determined from the exponential model was predictive of a negative outcome.

Adenovirus-mediated transfer of inducible caspases: a novel "death switch" gene therapeutic approach to prostate cancer

In patients with localized prostate cancer, radical prostatectomy and radiation therapy, although effective in controlling localized disease, are often associated with significant side effects attributable to injury of adjacent tissues. Moreover, patients with metastatic disease eventually fail systemic hormonal or chemotherapy because of the development of progressive, refractory disease. In this study, we evaluated the safety and efficacy of a novel suicide gene therapy that could potentially spare normal tissue while bypassing molecular mechanisms of apoptosis resistance by using chemically inducible effector caspases to trigger apoptosis in prostate cancer cells. Initially, we compared the ability of a panel of inducible Fas signaling intermediates to kill human and murine prostate cancer cell lines. On the basis of the superior killing by downstream caspase-1 and caspase-3, replication-deficient adenoviral vectors expressing conditional caspase-1 (Ad-G/iCasp1) or caspase-3 (Ad-G/iCasp3), regulated by nontoxic, lipid-permeable, chemical inducers of dimerization (CID), were constructed. Upon vector transduction followed by CID administration, aggregation and activation of these recombinant caspases occur, leading to rapid apoptosis. In vitro, both human (LNCaP and PC-3) and murine (TRAMP-C2 and TRAMP-C2G) prostate cancer cell lines were efficiently transduced and killed in a CID-dependent fashion. In vivo, direct injection of Ad-G/iCasp1 into s.c. TRAMP-C2 tumors caused focal but extensive apoptosis without evidence for a bystander effect at the maximal viral dose (i.e., 2.5 x 10(10) viral particles/25 microl) in host animals that also received CID compared with control animals. Treatment with Ad-G/iCasp1 plus CID resulted in a transient, yet significant, reduction both in tumor growth and volume compared with tumors treated with vector but not CID (P < 0.035) or vector-diluent plus CID (P < 0.022), both of which grew more rapidly. These results demonstrate that CID-regulated, caspase-based suicide gene therapy is safe and can inhibit the growth of experimental prostate cancer in vitro and in vivo through potent induction of apoptosis, providing a rationale for further development.

Research and development of an implantable, axial-flow left ventricular assist device: the Jarvik 2000 Heart

Advances in technology and increased clinical need have led to the development of a new type of blood pump. The Jarvik 2000 Heart is an electrically powered, axial-flow left ventricular assist device that has been developed during the past 13 years. Unlike first-generation left ventricular assist devices, which were developed in the 1970s and were designed to totally capture the cardiac output, the Jarvik 2000 is designed to normalize the cardiac output by augmenting the function of the chronically failed heart for extended periods. Design iterations have been tested in 67 animals, and clinical trials have recently begun. Three patients have received the Jarvik 2000 as a bridge to transplantation, and 1 patient is being supported permanently outside the hospital. All 4 patients have improved from New York Heart Association functional class IV to class I, and 2 of them have been discharged from the hospital after heart transplantation. The experimental and clinical results indicate that the Jarvik 2000 can provide physiologic support with minimal complications and is reliable, biocompatible, and easy to implant.

Simultaneous measurement of hepatic tissue pH, venous oxygen saturation and hemoglobin by near infrared spectroscopy

The purpose of this study was to investigate the feasibility of using near infrared (NIR) spectroscopy of the liver to simultaneously assess oxygen content in combination with tissue pH, an indicator of anaerobic metabolism. Six anesthetized swine were subjected to 45 min of hemorrhagic shock followed by resuscitation with blood and crystalloid. Calibration models between NIR spectra and reference measurements of tissue pH, hepatic venous oxygen saturation (S(V)O2), and blood hemoglobin concentration (Hb) were developed using partial least-squares regression. Model accuracy was assessed using cross validation. The average correlation (R2) between NIR and reference measurements was 0.87, 0.68, and 0.93, respectively for pH, Hb, and S(V)O2. Estimated accuracy, the root mean squared deviation between spectral, and reference measurements was 0.03 pH units, 0.3 g/dL, and 6%. NIR determination of hepatic oxygen content and tissue pH during shock and resuscitation demonstrated that there can be a variance between hepatic venous oxygenation and regional tissue acidosis. NIR spectroscopy provides a technique to explore the implications of post-shock depression of tissue pH and evaluate new methods of resuscitation.

A national survey of policies on disclosure of conflicts of interest in biomedical research

BACKGROUND

Conflicts of interest pose a threat to the integrity of scientific research. The current regulations of the U.S. Public Health Service and the National Science Foundation require that medical schools and other research institutions report the existence of conflicts of interest to the funding agency but allow the institutions to manage conflicts internally. The regulations do not specify how to do so.

METHODS

We surveyed all medical schools (127) and other research institutions (170) that received more than $5 million in total grants annually from the National Institutes of Health or the National Science Foundation; 48 journals in basic science and clinical medicine; and 17 federal agencies in order to analyze their policies on conflicts of interest.

RESULTS

Of the 297 institutions, 250 (84 percent) responded by March 2000, as did 47 of the 48 journals and 16 of the 17 federal agencies. Fifteen of the 250 institutions (6 percent)--5 medical schools and 10 other research institutions--reported that they had no policy on conflicts of interest. Among the institutions that had policies, there was marked variation in the definition and management of conflicts. Ninety-one percent had policies that adhered to the federal threshold for disclosure ($10,000 in annual income or equity in a relevant company or 5 percent ownership), and 9 percent had policies that exceeded the federal guidelines. Only 8 percent had policies requiring disclosure to funding agencies, only 7 percent had such policies regarding journals, and only 1 percent had policies requiring the disclosure of information to the relevant institutional review boards or to research subjects. Twenty journals (43 percent) reported that they had policies requiring disclosure of conflicts of interest. Only four federal agencies had policies that explicitly addressed conflicts of interest in extramural research, and all but one of the agencies relied primarily on institutional discretion.

CONCLUSIONS

There is substantial variation among policies on conflicts of interest at medical schools and other research institutions. This variation, combined with the fact that many scientific journals and funding agencies do not require disclosure of conflicts of interest, suggests that the current standards may not be adequate to maintain a high level of scientific integrity.

Infectious complications associated with ventricular assist systems

Infectious complications during support with a ventricular assist system (VAS) can cause severe morbidity and mortality, affecting nearly one-half of all VAS recipients. Because of the lack of a uniform definition of infection, the incidence of this complication is hard to determine accurately. It is approximately 50% for patients being supported by an implantable VAS as a bridge to heart transplantation and 28% for patients supported by an external, short-term VAS. Infections can be classified according to the involvement or noninvolvement of the implanted device and according to the severity of the infection. Severe infections involving the implanted device may preclude heart transplantation for some patients, but numerous patients with milder infections have undergone successful transplantation. Numerous factors predispose VAS patients to infection. Postoperative bleeding necessitating re-operation is an important contributing factor. Endotracheal tubes, intravascular catheters, and other indwelling tubes necessary for the care of postsurgical patients are also common routes of contamination. Control of infection may be improved with new VAS designs, antibiotic impregnated drivelines, and innovative therapies such as antibiotic beads. The next generation of VASs should be inherently less susceptible to infection because of their smaller size, reduced thrombogenicity, and better flow characteristics. In addition to more effective antibiotics, improved VAS designs that incorporate transcutaneous energy transmission systems may reduce infectious complications and allow safe, long-term VAS support.

Mechanical, bioadhesive strength and biological evaluations of chitosan films for wound dressing

PURPOSE

To investigate the suitability of chitosan films prepared using two different solvents, acetic acid (Chitosan-AA) and lactic acid (Chitosan-LA), for wound dressing, in comparison with a commercial preparation, Omiderm.

METHODS

The mechanical and in-vitro bioadhesive strength properties of Chitosan-AA, Chitosan-LA, and Omiderm were investigated using texture analyzer equipment. The vapour permeability of chitosan films was determined using a method for evaluation of moisture permeability of containers and packaging material described in USP XXII. In addition, the biological evaluations were performed via primary skin irritation, intracutaneous, and systemic injection tests.

RESULTS

The three preparations differed significantly in terms of the mechanical and bioadhesive strength properties. Chitosan-LA exhibited a lower tensile strength, but more flexible and bioadhesive than Chitosan-AA. Chitosan film was found to be permeable to water vapour. Chitosan-LA and Omiderm were non-irritant and did not cause any skin allergic reaction. In contrast, Chitosan-AA films inflicted adverse skin reactions. Nevertheless, no gross sign of toxicity was encountered from the systemic injection of the extracts of the three preparations.

CONCLUSION

Chitosan films demonstrated significantly different mechanical and bioadhesive strength properties from Omiderm. Chitosan-LA was more soft, flexible, pliable and bioadhesive when compared to Chitosan-AA films. Furthermore, Chitosan-LA did not cause erythema, edema and systemic toxicity. Hence, Chitosan-LA film is suitable to be used in the management of wound healing and skin burn.

Assessment of endothelium-mediated vasodilation of the peripheral circulation by transcutaneous ultrasonography and venous occlusion plethysmography

Transcutaneous ultrasonography is a non-invasive technique with the ability to measure the volumetric blood flow of the peripheral circulation. Peripheral blood flow can be determined by high-resolution imaging of vessel diameter coupled with Doppler assessment of flow velocity. This method, however, has not been validated in vivo. Accordingly, brachial artery flow in response to intraarterial infusion of vasodilators was assessed by ultrasonography in 16 healthy subjects and compared to values obtained simultaneously by venous occlusion plethysmography. Blood flow calculated from ultrasound-derived vessel diameter and flow velocity was found to highly correlate with plethysmographic flow, with r values ranging from 0.83 to 0.99. Using this ultrasound technique combined with plethysmography, the response of conduit and resistance vessels to endothelium-mediated vasodilation was characterized. Doppler velocity rose dramatically with endothelium-dependent acetylcholine (970%), but only modestly with endothelium-independent vasodilators, nitroglycerin (292%) and nitroprusside (340%). Despite eliciting the greatest overall forearm flow response, acetylcholine resulted in a smaller increase in conduit diameter (15.4%) than nitroglycerin (21.8%), and only a comparable change than nitroprusside (14.6%). Taken together, these results suggest that acetylcholine acts predominantly on resistance vessels, whereas nitrovasodilators affect mainly conduit vessels. In summary, transcutaneous ultrasonography can be used reliably to assess flow changes in the peripheral circulation. Combined with plethysmography, this technique is useful for determining the relative contribution of conduit and resistance vessels to peripheral flow, particularly in the assessment of endothelium-mediated vasodilation.

Hair loss in psychopharmacology

Medication-induced alopecia is an occasional side effect of many psychopharmaceuticals. Most of the mood stabilizer and antidepressant drugs can lead to this condition. Some antipsychotic and antianxiety agents induce alopecia. Hair loss is also related to hypothyroidism, which can be induced by lithium and other agents. Alopecia might not be reported by some people, but physicians should be aware of this potential problem which may contribute to noncompliance. Lithium causes hair loss in 12-19% of long-term users. Valproic acid and/ or divalproex precipitates alopecia in up to 12% of patients in a dose-dependent relationship. Incidences up to 28% are observed with high valproate concentration exposures. These pharmaceuticals also can change hair color and structure. The occurrence of carbamazepine-induced alopecia is at or below 6%. Hair loss is less common with other mood stabilizers. Tricyclic antidepressants, maprotilene, trazodone, and virtually all the new generation of antidepressants may on rare occasions lead to alopecia. The same applies to haloperidol, olanzepine, risperidone, clonazepam, and buspirone, but not to other neuroleptics, benzodiazepines, or barbiturates, selected antihistamines, and antiparkinsonians. Discontinuation of the medication or dose reduction almost always leads to complete hair regrowth. The therapeutic value of mineral supplements remains unclear.

Phytochemical study of Salvia moorcroftiana

Four known flavonoids were isolated from the aerial parts of Salvia moorcroftiana.

Regulation of the contact sensitivity response to urushiol with anti-urushiol monoclonal antibody ALG 991

The objective of the studies was to demonstrate that the contact sensitivity (CS) response to poison ivy/oak could be downregulated following treatment with a monoclonal antibody (mAb) reacting with the allergen urushiol. Conjugation of urushiol and its synthetic analogue 3-n-pentadecylcatechol (PDC) to N-acetylcysteine yielded hydrosoluble derivatives which induced humoral immune responses in BALB/c mice. Hybridomas secreting monoclonal antibodies (mAbs) reacting with urushiol and PDC were generated by fusion of B lymphocytes from immunized mice with mouse myeloma P3NS0 cells. The specificity of mAb ALG 991 (IgM isotype) was defined by inhibition of antibody binding by PDC analogues. This demonstrated that mAb ALG 991 reacted with the catechol moiety of urushiol, the region of the allergen being critically important in the induction of contact dermatitis. The CS response to urushiol in BALB/c mice was suppressed by stimulation with mAb ALG 991 and the role of sensitized T cells, including suppressor T cells, has been considered. Suppression of CS was most effective with low doses (1 microg) of mAb incorporated into a vaccine with Freund's adjuvant. This treatment suppressed CS responses in BALB/c mice already sensitized to urushiol.

Improved artificial death switches based on caspases and FADD

A number of "suicide genes" have been developed as safety switches for gene therapy vectors or as potential inducible cytotoxic agents for hyperproliferative disorders, such as cancer or restenosis. However, most of these approaches have relied on foreign proteins, such as HSV thymidine kinase, that primarily target rapidly dividing cells. In contrast, novel artificial death switches based on chemical inducers of dimerization (CIDs) and endogenous proapoptotic molecules function efficiently in both dividing and nondividing cells. In this approach, lipid-permeable, nontoxic CIDs are used to conditionally cross-link target proteins that are fused to CID-binding domains (CBDs), thus activating signaling cascades leading to apoptosis. In previous reports, CID-regulated Fas and caspases 1, 3, 8, and 9 were described. Since the maximum efficacy of these artificial death switches requires low basal and high specific activity, we have optimized these death switches for three parameters: (1) extent of oligomerization, (2) spacing between CBDs and target proteins, and (3) intracellular localization. We describe improved conditional Fas and caspase 1, 3, 8, and 9 alleles that function at subnanomolar levels of the CID AP1903 to trigger apoptosis. Further, we demonstrate for the first time that oligomerization of the death effector domain of the Fas-associated protein, FADD, is sufficient to trigger apoptosis, suggesting that the primary function of FADD, like that of Apaf-1, is oligomerization of associated caspases. Finally, we demonstrate that nuclear-targeted caspases 1, 3, and 8 can trigger apoptosis efficiently, implying that the cleavage of nuclear targets is sufficient for apoptosis.

Carbon filaments direct the growth of postlesional plastic axons after spinal cord injury

The effect of implantation of carbon filaments and fetal tissues on the axonal regeneration following contusion injury in a rat model was investigated by in situ immunofluorescence. Female Sprague-Dawley rats were subjected to severe contusion injury to the spinal cord at T9-T10. All animals were divided into 5 groups (N = 5/group): normal controls. surgical controls, with carbon filament implants, with fetal tissue implants and with implants consisting of fetal tissue cocultured with carbon filaments. After a 10-week survival period, the astroglial response was assessed by immunoreactive glial fibrillary acidic protein and the neuro-axonal profile by immunoreactive phosphorylated and nonphosphorylated neurofilament proteins. The contusion injury resulted in: (a) dramatically increased immunoreactivity of glial fibrillary acidic protein indicating injury-associated reactive astrogliosis, (b) increase in immunoreactive phosphorylated neurofilament protein indicating upregulated phosphorylation of neurofilament protein, (c) with no change in the highly differentiated nonphosphorylated neurofilament protein which normally occur in the nonregenerating mature neurons. Implantation of fetal tissues alone following contusion injury did not show any appreciable change with regard to the immunoreactivities for the glial and neuronal markers studied, compared to the injury controls. However, the implantation of carbon filaments alone or together with fetal tissues directed the growth of glial fibrillary acidic protein-positive astroglia and phosphoneurofilament-positive neurites along the carbon fibers, with no effect on nonphosphoneurofilament protein. In conclusion, implantation of carbon filaments appears to be critical for facilitating the attachment of astroglia forming a substrate and scaffolding that can further support and direct the growth of postlesional plastic axons across the lesion. In addition, carbon filament prostheses in combination with fetal tissue implants provides an improved combinational approach to promote regrowth of injured neurons following injury.

Decreased activity of the L-arginine-nitric oxide metabolic pathway in patients with congestive heart failure

BACKGROUND

Impaired endothelium-dependent, nitric oxide (NO)-mediated vasodilation may contribute to increased vasomotor tone in patients with heart failure. Whether decreased endothelium-dependent, NO-mediated vasodilation in patients with heart failure is due to decreased synthesis or increased degradation of NO is unknown.

METHODS AND RESULTS

To specifically assess the synthetic activity of the L-arginine-NO metabolic pathway, urinary excretion of [15N]nitrates and [15N]urea was determined after a primed continuous intravenous infusion of L-[15N]arginine (40 micromol/kg) in 16 patients with congestive heart failure and 9 age-matched normal control subjects at rest and during submaximal treadmill exercise. After infusion of L-[15N]arginine, 24-hour urinary excretion of [15N]nitrates was decreased in patients with congestive heart failure at rest (2.2+/-0.5 versus 8.0+/-2.3 micromol/24 h) and during submaximal exercise (2.4+/-1.2 versus 11. 4+/-4.0 micromol/24 h) compared with control subjects (both P<0.01). After infusion of L-[15N]arginine, 24-hour urinary excretions of [15N]urea at rest in patients with congestive heart failure and control subjects were not different (1.1+/-0.3 versus 1.2+/-0.2 mmol/24 h, P>0.20).

CONCLUSIONS

A specific decrease in synthetic activity of the L-arginine-NO metabolic pathway contributes to decreased endothelium-dependent vasodilation in patients with congestive heart failure.

Animal models of spinal cord contusion injuries

BACKGROUND AND PURPOSE

Traumatic spinal cord injury causes initial mechanical disruption of tissue, leading to a complex secondary sequence of pathophysiologic changes and neurologic impairment. These sequelae depend on the impact force delivered to the spinal cord at the time of injury. Successful clinical evaluation of the efficacy of any therapeutic regimen depends on the reliability and reproducibility of an experimental animal model. We describe a trauma device and the biomechanical parameters required to induce severe or moderate spinal cord contusion injury in cats and rats.

METHODS

Recovery after injury was determined by behavioral, electrophysiologic, and histologic evaluations.

RESULTS

Behavioral and electrophysiologic tests after injury clearly identified the experimental groups. A stable severe paraplegic state (defined as 6 months for cats and 8 weeks for rats), without evidence of behavioral or electrophysiologic recovery, was induced by a 65-Newton (N) load for cats and a 35-N load for rats. Moderate spinal cord contusion injury, from which cats and rats partially recovered after approximately 3 months and 4 weeks, respectively, was induced by a 45- and 25-N load, respectively.

CONCLUSION

Use of these injury conditions provides reliable animal models for studies designed to evaluate potential therapeutic regimens for spinal cord injury.

The effect of glutamate uptake inhibitors on hippocampal evoked potentials in vitro

The influence of four inhibitors of the high-affinity glutamate uptake system (DL-aspartic acid beta-hydroxymate, DL-AHM; L-aspartic acid beta-hydroxymate, L-AHM; threo-beta-methylaspartate, DLM; L-transpyrrolidine-2, 4-dicarboxylate, PDC) on potentials recorded from hippocampal slices was investigated. At low concentrations of DL-AHM, L-AHM and DLM (50-150 microM) the population spike was permanently amplified. NMDA receptor antagonists blocked this facilitatory effect of L-AHM, DL-AHM and DLM. At higher concentrations (400-700 microM) DL-AHM and DLM abolished the population spike, while L-AHM did not eliminate the population spike at any concentration tested. None of these uptake inhibitors influenced an antidromic potential recorded in Ca(2+)- free Ringer solution. PDC at lower concentrations (75 microM) did not affect the population spike and at higher concentrations (150 microM-500 microM) induced only a transient elevation in population spike. Our data demonstrate that modification of glutamate uptake may be an important factor in the regulation of synaptic efficiency of glutamergic pathways.

Scar quality from partial or complete wound closure using the Cincinnati incision for clubfoot surgery

The method of skin closure in using the Cincinnati incision for clubfoot surgery may influence the quality of the scar obtained and the postoperative outcome. We retrospectively reviewed two groups of patients who underwent either primary skin closure (14 feet in 11 patients) or partial wound closure and healing by secondary intention (15 feet in 11 patients). The quality of the scars from both of these methods were equally acceptable cosmetically, and neither technique predisposed the patient to any long-term wound complications. In addition, we noted that closing the skin may act as a soft tissue tether, and that the initial position of the postoperative splinting of the foot may influence the surgical outcome. Both of these factors may contribute to the recurrence of equinovarus deformity.

Preparation of brain-derived neurotrophic factor- and neurotrophin-3-secreting Schwann cells by infection with a retroviral vector

One reason that the central nervous system of adult mammals does not regenerate after injury is that neurotrophic factors are present only in low concentrations in these tissues. Recent studies have shown that the application of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) acts to encourage the regrowth of motor and sensory fibers after spinal cord injury. Other studies have reported that the regrowth of axons after injury was enhanced by the implantation of Schwann cells, which normally secrete BDNF and NT-3. The purpose of the present study was to genetically modify Schwann cells to secrete increased amounts of BDNF or NT-3 by infection with a retroviral vector. Retroviral vectors were constructed by the ligation of BDNF or NT-3 cDNA to the LXSN vector. Viruses were generated from the plasmid forms of the vectors by transient transfection of PA317 amphotrophic retroviral packaging cells. Viruses were harvested and used to infect the human Schwann cell line designated NF-1T. Northern blot analysis of poly (A+) RNA prepared from Schwann cells that were infected with BDNF- or NT-3-containing virus showed the presence of BDNF or NT-3 mRNA. An enzyme-linked immunosorbent assay (ELISA) for BDNF and NT-3 was performed on media the cells were grown in, and on cellular extracts prepared from the BDNF- and NT-3-infected Schwann cells. The ELISA results demonstrated that the Schwann cells were secreting increased levels of immunologically active BDNF or NT-3. Immunocytochemical staining of these cells revealed the presence of these two neurotrophic factors located in perinuclear granules. These neurotrophic factor-secreting Schwann cells are currently being evaluated for their efficacy in the treatment of spinal cord injury.

Apoptosis induced by gliotoxin is preceded by phosphorylation of histone H3 and enhanced sensitivity of chromatin to nuclease digestion

The fungal toxin gliotoxin induces apoptotic cell death in a variety of cells. Apoptosis induced in thymocytes by gliotoxin is rapid, and DNA fragmentation is observable within 4 h treatment. Apoptosis induced by gliotoxin is calcium-independent and unaffected by protein synthesis inhibitors. We have previously shown that gliotoxin results in phosphorylation of a 16.3-kDa protein within 10 min treatment of thymocytes. Here we show that this protein is histone H3 and phosphorylation occurs on Ser-10. Cyclic AMP levels and activity of protein kinase A (PKA) are raised in cells treated with gliotoxin. Apoptosis is inhibited by genistein which also inhibits PKA and histone H3 phosphorylation. Apoptosis is also inhibited by a number of specific inhibitors of PKA suggesting apoptosis induced by gliotoxin is modulated by this kinase. The agents forskolin and cholera toxin do not induce rapid phosphorylation of H3 although some increase in phosphorylation of H3 does occur after 8 h with these agents. Forskolin and cholera toxin also induce apoptosis but over a longer time course than gliotoxin. In all cases levels of apoptosis correlate with degree of H3 phosphorylation. Cells treated with gliotoxin show an early sensitivity to micrococcal nuclease and DNase I digestion indicating a functional relationship between DNA fragmentation and H3 phosphorylation.

Delayed reversal of impaired metabolic vasodilation in patients with end-stage heart failure during long-term circulatory support with a left ventricular assist device

BACKGROUND

Whether increased cardiac output during chronic circulatory support with a left ventricular assist device (LVAD) is associated with improved metabolic vasodilation in the peripheral circulation of patients with congestive heart failure is unknown.

METHODS

Forearm blood flow, determined by venous occlusion plethysmography, mean arterial pressure, and cardiac output were measured at rest and after 5 minutes of arterial occlusion (a maximal metabolic vasodilatory stimulus) in 14 patients with severe heart failure before LVAD implantation, and in the early (<4 weeks) and late (8 to 12 weeks) postoperative recovery phases after LVAD implantation. Nine normal subjects served as controls. Vascular conductance was calculated as the ratio of forearm blood flow and mean arterial pressure.

RESULTS

Mean arterial pressure and cardiac output increased to normal values in the early and late recovery phases after LVAD implantation. Resting forearm blood flow and vascular conductance were similar to normal subjects in the early and late recovery phases after LVAD implantation. Peak forearm blood flow and vascular conductance were significantly less than control subjects in the early preoperative recovery phase (p < 0.05) but were similar to control subjects in the late postoperative recovery phase after LVAD implantation.

CONCLUSIONS

In spite of early normalization of cardiac output, mean arterial pressure, and resting forearm blood flow during chronic circulatory support with the LVAD, peak forearm blood flow, and peak vascular conductance did not increase to values similar to those observed in normal subjects until the late postoperative recovery period. The delayed effect of the LVAD on metabolic vasodilation may be related to flow-dependent changes in the peripheral vasculature of patients with heart failure.

Acetyl-L-carnitine effects on nerve conduction and glycemic regulation in experimental diabetes

Acetyl-L-Carnitine (ALC), an activator of carnitine, can accelerate nerve regeneration after experimental surgical injury in rats. In this study, we examined the ability of ALC to improve nerve conduction velocity and its effect on intravenous glucose tolerance test in streptozotocin-induced diabetic rats. Diabetic (blood glucose > 200 mg%) and normal animals were treated intraperitoneally for four weeks with ALC, 50 mg/Kg/d and 150 mg/Kg/d. Nerve conduction velocity was measured by direct exposure of sural nerve. Two-hour IVGTT was studied by measuring plasma glucose, insulin and free fatty acids after intravenous injection of glucose, 1.75 gm/Kg/body weight in animals treated either with ALC 150 md/Kg/d or saline alone. Six weeks of STZ-induced diabetes resulted in impairment of nerve conduction velocity in animals injected with saline (16.05 +/- 1.09 m/s), as compared to saline-treated normals who did not receive streptozotocin (31.0 +/- 0.84 m/s, p<0.0005). Diabetic animals treated with ALC, 150 mg/Kg/d, preserved near normal nerve conduction (27.10 +/- 1.42 m/s), compared with the saline-treated diabetic animals (p < 0.0005), but diabetic animals treated with ALC, 50 mg/Kg/d, had a non-significant increase in nerve conduction (23.68 +/- 1.6). ALC treatment had no effect on fasting or post-intravenous plasma glucose in normal or diabetic rats, although it moderately reduced baseline and 40 minute insulin levels (p < 0.02) in normal rats as compared with their saline-treated counterparts. ALC treatment lowered baseline free fatty acids in normal (p < 0.04) and diabetic (p < 0.03) animals, and the 60 minute levels in the normal group only (p < 0.003).

CONCLUSION

ALC at a dose of 150 mg/Kg/d given for one month, produced near normalization of nerve conduction velocity in streptozotocin-induced diabetes with no adverse effects on glucose, insulin or free fatty acid levels.

Do direct current electric fields enhance micturition in the spinal cat?

Changes in micturition behavior and motoneuron ultrastructure were studied in spinal cats to determine the effects of direct current (DC) electric field treatment. Adult cats received a complete injury at T8. A treatment group with an implanted 15 microA DC source and electrodes positioned near the lesion site was compared with non-treatment groups that were either operated or unoperated. Both bladder emptying with Crede and the withdrawal reflex were improved in the treatment group compared with the non-treatment group. Urodynamic procedures showed that high urethral resistance and pelvic floor activity following spinal injury was partially reduced in the stimulated cat, indicating inhibition of the urethral sphincter. The ultrastructural analysis of Onuf's nucleus suggested a similar synaptic input in all three groups. In conclusion, possible activation of inhibitory processes and/or neural plasticity best explain the early improvement of bladder function seen following electrical stimulation.

Exercise-induced vasodilation in forearm circulation of normal subjects and patients with congestive heart failure: role of endothelium-derived nitric oxide

OBJECTIVES

This study was undertaken to investigate the role of endothelium-derived nitric oxide in the regulation of forearm blood flow during exercise in normal subjects and patients with congestive heart failure.

BACKGROUND

Nitric oxide-mediated vasodilation in response to muscarinic stimulation is impaired in the peripheral circulation of patients with congestive heart failure. Whether nitric oxide-mediated vasodilation during exercise is also impaired in patients with congestive heart failure is unknown.

METHODS

Forearm blood flows (ml/min per 100 ml) were determined during rhythmic hand grip exercise at 15%, 30% and 45% of maximal voluntary contraction by venous occlusion plethysmography before and after regional inhibition of nitric oxide synthesis with administration of L-NG-monomethylarginine (L-NMMA) in the brachial artery of 17 patients with congestive heart failure (mean age 49 years, mean left ventricular ejection fraction 0.22) and 10 age-matched normal subjects.

RESULTS

Before administration of L-NMMA in the brachial artery, forearm blood flows in patients with congestive heart failure during rhythmic hand grip exercise at 15%, 30% and 45% of maximal voluntary contraction were slightly but not significantly lower than that of normal subjects ([mean +/- SE] 6.8 +/- 1.0, 8.5 +/- 1.0 and 12.9 +/- 1.7 ml/min per 100 ml, respectively, in patients with congestive heart failure vs. 6.6 +/- 1.2, 11.6 +/- 1.9 and 16.2 +/- 1.9 ml/min per 100 ml, respectively, in normal subjects, p = NS). After administration of L-NMMA in the brachial artery, forearm blood flows in normal subjects significantly decreased by 10% to 21% during hand grip exercise but did not change during exercise in patients with congestive heart failure.

CONCLUSIONS

Regional inhibition of nitric oxide synthase with administration of L-NMMA in the brachial artery significantly decreased forearm blood flows during rhythmic hand grip exercise in normal subjects but not in patients with congestive heart failure. These findings suggest that nitric oxide-mediated vasodilation during submaximal exercise is impaired in the forearm circulation of patients with congestive heart failure.

Multiple mechanisms may contribute to the cellular anti-adhesive effects of phosphorothioate oligodeoxynucleotides

Phosphorothioate oligodeoxynucleotides complementary to the p65 (Rel A) subunit of the NF-kappaB nuclear transcriptional regulatory factor have been suggested to be sequence specific blockers of cellular adhesion. We studied the effects of Rel A antisense, Rel A sense and other phosphorothioate oligodeoxynucleotides on cellular adhesion and found that blockade of adhesion was predominately non-sequence specific. Phosphorothioate oligodeoxynucleotides bind to the extracellular matrix (ECM) of NIH 3T3 cells, and to the ECM elements laminin and fibronectin. By use of a gel mobility shift assay, the association of the A subunit of laminin with a probe 12mer phosphodiester oligodeoxynucleotide could be demonstrated. This interaction was described by a single-site binding equation (K d = 14 microM). Human Rel A antisense and sense oligodeoxynucleotides, and two synthetic persulfated heparin analogs were excellent competitors of the binding of the probe oligodeoxynucleotide to laminin. Taken together, these data indicate that oligodeoxynucleotide binding occurred at or near the heparin-binding site. Competition for 5' 32p- SdT18 (an 18mer phosphorothioate homopolymer of thymidine) binding to fibronectin with the discrete heparin analogs, as well as with SdC28, was also observed. Phosphorothioate oligodeoxynucleotides (Rel A antisense >> Rel A sense) inhibited the binding of laminin to bovine brain sulfatide, but not to its cell surface receptors on MCF-7 cells. By flow cytometric analysis we have also shown, in contrast to what was observed with laminin, that phosphorothioates a non-specifically block the specific binding of fluoresceinated fibronectin to its cell surface receptors on phorbol-12,13-myristate acetate treated Jurkat cells. Blockade of specific binding occurred in the oligodeoxynucleotide treated cells in the presence or absence of oligomer in the media.

Electrophysiological improvement after co-implantation of carbon filaments and fetal tissue in the contused rat spinal cord

The electrophysiological integrity of the adult rat spinal cord was assessed at the lumbar, lower cervical and cortical levels after the animals sustained a severe contusion injury at the mid-thoracic level (T8) and received either carbon filament cultured with fetal spinal cord tissue implants, fetal tissue implants, or carbon filament implants alone. Somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) were recorded from all animal groups at the end of the 8-week survival period. The results of this study demonstrate that the spinal cord injured animals that received carbon filament cultured with fetal spinal cord tissue implants had the highest degree of electrophysiological recovery, indicating that this combination plays an important role in promoting recovery after injury.

Effectiveness of the lactational amenorrhea method in Pakistan

OBJECTIVE

To determine the efficacy of the lactational amenorrhea method of family planning (amenorrhea during full or nearly full breastfeeding for 6 months postpartum).

DESIGN

Prospective noncomparative study.

SETTING

Normal breastfeeding women in Karachi and Multan, Pakistan, most delivered at home by a midwife.

PATIENTS

Three hundred ninety-nine newly delivered mothers who successfully had breastfed a previous child and chose the lactational amenorrhea method to prevent a subsequent pregnancy, 391 of whom were followed for a full year.

INTERVENTIONS

Mothers were taught, before or shortly after delivery, to use the method and were interviewed in their homes each month by a Lady Health Visitor.

MAIN OUTCOME MEASURE

Life-table pregnancy rates. Periods of postpartum or lactational abstinence were excluded in the calculation of the pregnancy rates.

RESULTS

During full or nearly full breastfeeding, while the women were amenorrheic and not otherwise contracepting, the rate of pregnancy was 0.6%. The pregnancy rate during lactational amenorrhea alone was 1.1% at 1 year postpartum.

CONCLUSION

The lactational amenorrhea method was found to be highly effective for 6 months. A high degree of contraceptive protection endures for a full year during lactational amenorrhea, but not after the return of menses during breastfeeding.

DNA synthesis precedes gliotoxin-induced apoptosis

The toxin gliotoxin induces apoptosis or programmed cell death in a variety of immune cells including thymocytes. Apoptosis induced by gliotoxin in thymocytes is unaffected by protein synthesis inhibitors nor is it associated with early changes in intracellular calcium levels (Beaver and Waring, 1994). This work shows that the cell lines P815 and WEHI7 and murine thymocytes when treated with gliotoxin show an early incorporation of tritiated thymidine over the concentration range which causes apoptosis. Proliferating cell nuclear antigen (PCNA), a marker for S phase, is elevated in cells following gliotoxin treatment and S phase DNA content is increased. Thymidine incorporation is inhibited by hydroxyurea, an inhibitor of replicative DNA synthesis not repair. Free radical scavangers have no effect on apoptosis induced by gliotoxin in thymocytes. Hydrogen peroxide-treated cells showed no enhanced thymidine incorporation and no apoptosis. Thus oxidative stress does not appear to be a factor in gliotoxin-induced apoptosis. Thymocytes treated with gliotoxin show increased phosphorylation of a 16.3 kDa protein, and apoptosis is inhibited by the tyrosine kinase inhibitor genistein, which also inhibited the increased thymidine incorporation in P815 cells. We conclude that one mechanism by which gliotoxin can cause apoptosis may be the induction of inappropriate entry of cells into the cell cycle followed by death.

Evaluation of a thin-film peripheral nerve cuff electrode

This is a study of the reaction of large nerves to implantation using a flexible, thin-film cuff electrode. Cuff electrodes were implanted on the sciatic nerve of three cats. An implantation period of six weeks allowed sufficient time for any injury responses in the nerve and connective tissue sheath around the cuff to develop. The electrode came off the nerve in one of the cats. In the remaining two cats, gross observation following explantation of the electrodes revealed encapsulation of the cuffs without swelling of nerve tissue. Histological evaluation did not demonstrate nerve injury. The nerve cuff electrodes, which are comprised of titanium and iridium coatings on a fluorocarbon polymer substrate, appeared unaffected by the implantation, and connective tissue encapsulation did not adhere to either the polymer substrate or metallization. Evaluation of the electrodes using activated iridium oxide charge injection sites in more extended studies is now being undertaken.

Electrical field distribution within the injured cat spinal cord: injury potentials and field distribution

This study investigated the spontaneous injury potentials measured after contusion or transection injury to the cat spinal cord. In addition, the distribution of electrical field potentials on the surface and within the spinal cord were measured following applied electrical fields after transection and contusion injuries. After transection of the spinal cord, the injury potentials were -19.8 +/- 2.6 mV; after contusion of the spinal cord, the injury potentials were -9.5 +/- 2.2 mV. These potentials returned to control values within 2.5-4h after injury. The electrical field distribution measured on the dorsal surface, as well as within the spinal cord, after the application of a 10 microA current, showed little difference between contusion and transection injuries. Scalar potential fields were measured using two configurations of stimulating electrodes: dorsal to dorsal (D-D), in which both electrodes were placed epidurally on the dorsal surface of the spinal cord, and ventral to dorsal (V-D), in which one electrode was placed dorsally and one ventrally. As reported in normal uninjured cats, the total current in the midsagittal plane for the D-D configuration was largely confined to the dorsal portion of the spinal cord; with the V-D configuration, the current distribution was uniform throughout the spinal cord. In the injured spinal cord, the equipotential lines midway between the stimulating electrodes have a wider separation than in the uninjured spinal cord. Because the magnitude of the electrical field E is equal to the current density J multiplied by the resistivity r, this suggests that either the current density is reduced or that the resistivity is reduced.

Electric field distribution within normal cat spinal cord

Electric currents of small magnitude have been used successfully to induce regrowth of injured spinal cord fibers. The purpose of this study was to determine the potentials and current density distributions on the surface, as well as within the spinal cord, after the application of exogenous electric fields. A 10 microA DC current was applied epidurally to the spinal cord using two different electrode configurations. The two electrode configurations studied were: anode and cathode dorsal (D-D) and anode ventral and cathode dorsal (V-D). Two types of recording electrodes were used to map the potentials on the surface and within the spinal cord. The recording system consisted of glass microelectrodes connected to differential amplifiers. The output was recorded on a polygraph. The current density was more localized on the dorsal surface of the spinal cord for the D-D configuration. In contrast, in the V-D configuration, the current density was greater near the anode on the ventral surface and near the cathode on the dorsal surface of the spinal cord. As a result of the anode being located ventrally, there was a more uniform current density distribution within the spinal cord.

Distribution of alpha 1 subunit isoform of (Na,K)-ATPase in the rat spinal cord

Three isoforms of the alpha subunit of (Na,K)-ATPase have been identified in the rat central nervous system. Using a probe specific for the alpha 1 isoform, mRNA levels were measured from five sections of the rat spinal cord using slot blot techniques. Assigning a value of 1 to the slope obtained from the cervical section, the upper thoracic section was 2.6 times higher; the midthoracic section was 4.5 times higher; the lower thoracic section was 2.6 times higher; and the lumbar section was 1.7 times higher. The results suggest that alpha 1 isoform mRNA levels are not uniform throughout the spinal cord. In situ hybridization techniques showed that alpha 1 isoform mRNA was diffusely abundant in glial and central canal ependymal cells, while labeled neurons were localized exclusively in laterally located anterior horn neurons in cervical, thoracic, and lumbar segments and in ventromedial neurons in mid-thoracic spinal cord. Also, dorsal root ganglia neurons were extensively labeled at all segments.

Macrophage adherence prevents apoptosis induced by ricin

Ricin, a lectin with potent protein synthesis inhibitory properties, has been known to cause morphological changes in epithelial cells typical of apoptosis (P. Waring et al., Med. Res. Rev. 11, 1-17 (1991)). In earlier preliminary experiments from this laboratory with murine macrophages and T-blasts (P. Waring, J. Biol. Chem. 265, 14,476-14,480 (1990)), it was shown that ricin induces regular DNA fragmentation, a biochemical event also associated with apoptosis. Here we confirm morphologically and by examination of DNA fragmentation that macrophages undergo apoptosis when treated with ricin in a dose-dependent manner. Ricin also inhibits adherence of macrophages to plastic surfaces but does not affect adherence of preadhered macrophages after 7 h of treatment. We also report that adherence significantly diminishes DNA fragmentation induced in macrophages by ricin but has no effect on ricin-induced inhibition of protein synthesis. From these results we may conclude that the property of ricin to induce apoptosis may not be related to its ability to inhibit protein synthesis in macrophages. Moreover, the anti-phagocytic activity of ricin may be a direct consequence of its ability to fragment DNA and induce apoptosis and not of its ability to inhibit protein synthesis. We also observed no immediate increase in Ca2+ concentration when macrophages were treated with ricin indicating that ricin-induced apoptosis may not involve the activation of a Ca2+ dependent endonuclease(s).

The influence of synthetic conditions on the stability of methotrexate-monoclonal antibody conjugates determined by reversed phase high performance liquid chromatography

Methotrexate (MTX) has been convalently attached to an IgG-type monoclonal antibody (791T/36) directed to tumour-associated antigen gp72. Conjugates were synthesized by the active ester method using MTX N-succinimidyl ester at various pH values (7.5-10.5). Following purification by gel filtration, high performance liquid chromatography was used to assess the free drug or its derivatives in samples of MTX-791T/36 conjugates previously treated (or not) with hydroxylamine. Quantitative analysis, performed on a reversed phase column (pore size 300 A) with isocratic acetonitrile-sodium acetate buffer (pH 4.8) as mobile phase, indicated no detectable amount of free methotrexate in hydroxylamine-treated conjugates even six months after their preparation. Similar observations were made with conjugates, whose synthesis were performed at pH greater than or equal to 10. In contrast, the presence of increasing amounts of drug/metabolite could be demonstrated in samples produced at lower pH values. Based on these findings, the pH-dependent kinetics of MTX release has been determined and used to design conditions under which stable MTX-791T/36 conjugates could be prepared without hydroxylamine reaction.