Serotonin reduces potassium current in rutabaga and wild-type Drosophila neurons

The Drosophila learning mutant rutabaga is defective in short-term memory and has a reduced intracellular cyclic adenosine monophosphate (cAMP) concentration. The delayed-rectifier potassium current (IKDR) was measured from cultured (2 days) wild-type and rutabaga neurons. IKDR was smaller in rutabaga neurons (382 +/- 41 pA) than in wild-type neurons (542 +/- 33 pA). IKDR was measured from neurons before and after addition of serotonin to the external solution. IKDR was reduced by serotonin in wild type (decreasing 37 +/- 7%) and rutabaga (decreasing 33 +/- 6%) neurons (single-cell studies). In the presence of serotonin, IKDR was smaller in rutabaga (218 +/- 24 pA) than in wild-type (426 +/- 35 pA) neurons (population studies). These results indicate that serotonin has affected IKDR so that the inherent difference between the two genotypes was preserved.     

Effect of erythropoietin therapy on polyneuropathy in predialytic patients

BACKGROUND: Peripheral neuropathy commonly develops in patients with advanced chronic renal failure. The uremic neuropathy is often subclinical and detectable only by electrophysiological studies. Receptors to erythropoietin (EPO) have been described on non-hematopoietic cells including neuronal cells. METHODS: In order to evaluate the effect of five months' EPO therapy on polyneuropathy in predialytic patients, nerve conduction studies (NCS) were done in 46 anemic predialytic patients without neurological complaints. In 22 (twelve non-diabetic and ten diabetic) neuropathy was detected and these patients were included in the study. After five months of subcutaneous EPO therapy NCSs were repeated. RESULTS: Hemoglobin increased significantly (p=0.0001) with no significant increase in plasma creatinine. Motor nerve conduction velocity (MNCV) and compound muscle action potentials (CMAP) of the ulnar nerve were normal before EPO therapy and at the end of the study. MNCV of the median, peroneal and tibial nerves improved significantly (p<0.05). CMAP of the median nerve rose significantly, to the normal range (p=0.01). Sensory nerve conduction velocity (SNCV ) and sensory nerve action potentials (SNAP) were reduced in all sensory nerves and did not improve. The improvement in non-diabetic patients was better than in diabetic patients. No significant correlation was found between the increase in hemoglobin and the improvement in MNCV. CONCLUSIONS: Subcutaneous EPO therapy improved motor polyneuropathy in uremic patients, especially non-diabetic individuals. The improvement in MNCV may reflect remyelination. This non-hematopoietic effect may be related to some direct action through EPO receptors on peripheral neuronal cells.     

Effect of novel benzoylphenylurea derivatives on DNA polymerase α activity using the synthesome-based in vitro model system

Six benzoylphenylurea (BPU) derivatives have been synthesized in Japan and extensively evaluated by the U.S. National Cancer Institute. They demonstrted potent antitumor activity in vitro against several cancer cell lines as well as in vivo against several tumor models. One of these agents, NSC639829, has now entered clinical trials. Studies have shown that these compounds are effective inhibitors of in vitro tubulin polymerization. The parent compound, NSC624548 (HO-221), has been shown to inhibit calf thymus DNA polymerase activity. In this study we examined the effects of four BPU derivatives (NSC624548, NSC639828, NSC639829, and NSC654259) on the activity of the synthesome-associated DNA polymerase , Escherichia coli DNA polymerase I, and calf thymus DNA polymerase .Among the compounds tested, only NSC624548 and NSC639828 inhibited the activities of E. coli DNA polymerase I and calf thymus DNA polymerase . Excess DNA polymerase I or DNA polymerase dramatically reduced the inhibition produced by these compounds. NSC624548 and NSC639828 also showed inhibitory effects of the synthesome-associated DNA polymerase similar to that produced upon using the purified E. coli and calf thymus enzymes. All of the four compounds did not show inhibitory effect on DNA polymerase . The similar pattern of inhibition these compounds exert on both the purified calf thymus and the synthesome-associated DNA polymerase offers further support for the validity of the DNA synthesome as a novel in vitro model system for studying anticancer drug action.     

Succinylcholine Dosage and Apnea-induced Hemoglobin Desaturation in Patients

Background: The authors examined the notion that a reduction in succinylcholine dose from 1 mg/kg to [almost equal to]0.6 mg/kg would allow a faster recovery of spontaneous ventilation and reduction in the incidence of hemoglobin desaturation during the period of apnea in simulated complete upper airway obstruction situations.

Methods: This prospective, randomized, double-blind study involved 60 patients. After preoxygenation to an end-tidal oxygen concentration >90%, patients were anesthetized with 2 [mu]g/kg fentanyl and 2 mg/kg propofol. After loss of consciousness, patients were randomly allocated to receive 0.56 or 1.0 mg/kg succinylcholine or saline (control group). Oxygen saturation was monitored continuously at the index finger. When the patient became apneic, the face mask was removed and the patient's airway was left unsupported. If the oxygen saturation decreased to 90%, the face mask was reapplied, and ventilation was assisted until the patient was awake. Time from injection of the study drug to the first visible spontaneous diaphragmatic movements was noted.

Results: Oxygen saturation decreased <90% in 45%, 65%, and 85% of patients in the control, 0.56 mg/kg, and 1.0 mg/kg succinylcholine groups, respectively (P = 0.03). Corresponding times (mean +/- SD) to spontaneous of diaphragmatic movements were 2.7 +/- 1.2, 4.8 +/- 2.5, and 4.7 +/- 1.3 min, respectively. These times were longer (P < 0.001) after either dose of succinylcholine compared with controls.     

Biochemical and Mechanical Characterization of Enzyme-Digestible Hydrogels

Albumin-cross-linked hydrogels were prepared by free radical polymerization using 1-vinyl-2-pyrrolidinone as a monomer and functionalized albumin as a crosslinking agent. The degree of chemical cross-linking was controlled by varying the degree of albumin functionality and the concentration of albumin. With emphasis placed on the potential use of these hydrogels for long-term oral drug delivery, gel characterization studies examined both the swelling and the mechanical properties in the absence and presence of pepsin. In the absence of pepsin, the equilibrium swelling ratio in simulated gastric fluid ranged from 17 to 55, depending on the degree of albumin functionality and the albumin concentration. Swelling was pH dependent at pH's greater than 7. The uptake of solvent into the dried hydrogels was determined to be Fickian. The integrity of swelling gels was dependent on the concentration of the functionalized albumin as well as on the degree of albumin functionality. In the presence of pepsin, a predominance of either surface or bulk degradation was observed, depending on the functionality of the albumin used as a cross-linker. Gel integrity during pepsin degradation also showed a marked dependence on the albumin functionality.     

Targeted elimination of prostate cancer by genetically directed human T lymphocytes

The genetic transfer of antigen receptors is a powerful approach to rapidly generate tumor-specific T lymphocytes. Unlike the physiologic T-cell receptor, chimeric antigen receptors (CARs) encompass immunoglobulin variable regions or receptor ligands as their antigen recognition moiety, thus permitting T cells to recognize tumor antigens in the absence of human leukocyte antigen expression. CARs encompassing the CD3zeta chain as their activating domain induce T-cell proliferation in vitro, but limited survival. The requirements for genetically targeted T cells to function in vivo are less well understood. We have, therefore, established animal models to assess the therapeutic efficacy of human peripheral blood T lymphocytes targeted to prostate-specific membrane antigen (PSMA), an antigen expressed in prostate cancer cells and the neovasculature of various solid tumors. In vivo specificity and antitumor activity were assessed in mice bearing established prostate adenocarcinomas, using serum prostate-secreted antigen, magnetic resonance, computed tomography, and bioluminescence imaging to investigate the response to therapy. In three tumor models, orthotopic, s.c., and pulmonary, we show that PSMA-targeted T cells effectively eliminate prostate cancer. Tumor eradication was directly proportional to the in vivo effector-to-tumor cell ratio. Serial imaging further reveals that the T cells must survive for at least 1 week to induce durable remissions. The eradication of xenogeneic tumors in a murine environment shows that the adoptively transferred T cells do not absolutely require in vivo costimulation to function. These results thus provide a strong rationale for undertaking phase I clinical studies to assess PSMA-targeted T cells in patients with metastatic prostate cancer.     

Bone mineral density of the spine and femur in healthy Saudis

The reference values of bone mineral density (BMD) were determined in healthy Saudis of both sexes and compared with US / northern European and other reference data. BMD was determined by dual-energy X-ray absorptiometry (DXA) at the lumbar spine and femur including subregions: trochanter, Wards triangle, and neck, in 1,980 randomly selected Saudis (age range 20–79 years; 915 males and 1,065 females) living in the Jeddah area. Age-related changes in BMD were similar to those described in US / northern European and Lebanese reference data. Decreases in BMD of males were evident (% per year): 0.3–0.8 (lumbar spine), 0.2–0.4 (femoral trochanter), 0.2–1.4 (Wards triangle), and 0.2–0.7 (femoral neck). Also, decreases in BMD of females were observed (% per year): 0.8–0.9 (lumbar spine), 0.7–0.9 (Wards triangle), and 0.3–0.7 (femoral neck). Using stepwise multiple regressions that included both body weight and height, the former had 2–4 times greater effect on BMD than the latter. Using the mean BMD of the <35-year-old group the T-score values were calculated for Saudis. The prevalence of osteoporosis in Saudis (50–79 years) at the lumbar spine using the manufacturers vs Saudi reference data was 38.3–47.7% vs 30.5–49.6 (P<0.000), respectively. Similarly, based on BMD of total femur, the prevalence of osteoporosis using the manufacturers vs Saudi reference data was 6.3–7.8% vs 1.2–4.7% (P<0.000), respectively. Saudis (50 years) in the lowest quartile of body weight exhibited higher prevalence of osteoporosis (25.6% in females and 15.5% in males) as compared to that of the highest quartiles (0.0% in females and 0.8% in males). The present study underscores the importance of using population-specific reference values for BMD measurements to avoid overdiagnosis and/or underdiagnosis of osteoporosis.     

Loss of seizure control due to anticonvulsant-induced hypocalcemia

OBJECTIVE: To report a case of loss of seizure control due to hypocalcemia resulting from long-term treatment with phenytoin and phenobarbital. CASE SUMMARY: A 32-year-old mentally retarded man presented with a 12-month history of loss of seizure control, after being seizure-free for 5 years on a fixed regimen of phenobarbital and phenytoin. He had been institutionalized at the age of 10 years and had received anticonvulsant drugs since he was diagnosed with tonic-clonic epilepsy 20 years ago. On investigation, serum concentrations of the anticonvulsant drugs were within the therapeutic range, indicating adequate medication dosages. Serum biochemistry was consistent with vitamin D deficiency: hypocalcemia, reduced 25-hydroxyvitamin D, increased alkaline phosphatase, and increased parathormone. Seizure control was regained after serum calcium had been normalized with administration of vitamin D and calcium. DISCUSSION: Antiepileptic drugs (AEDs) cause vitamin D deficiency through induction of hepatic microsomal enzymes that metabolize vitamin D. Institutionalized subjects are more vulnerable because of the added factors of multidrug therapy, poor diet, reduced exposure to sunlight, and physical inactivity. The resulting hypocalcemia can cause reactive seizures, thus offsetting the anticonvulsant action of the drugs. An objective causality assessment revealed that the adverse reactions of both phenobarbital and phenytoin were probable. CONCLUSIONS: Hypocalcemic seizures are uncommon and underdiagnosed complications of long-term therapy with AEDs. Loss of seizure control in a patient stabilized on AEDs is an indication to check the patient's calcium status. Proper treatment of this complication is vitamin D and calcium supplementation. Prophylactic supplementation with vitamin D is necessary in institutionalized patients treated with AEDs.