Neuromuscular transmission and muscle contractility in SNAP-25-deficient coloboma mice

Synaptosomal associated protein of 25 kDa (SNAP-25) is a cytoplasmic protein that participates in the docking and fusion of synaptic vesicles with the nerve terminal in preparation for neurotransmitter release. SNAP-25 is also a substrate for three of the seven serotypes of botulinum neurotoxin (BoNT). Intoxication by BoNT/A, /C1 or /E results in weakness and paralysis of skeletal muscle due to cleavage of SNAP-25 (and syntaxin la in the case /C1) at discrete serotype-specific sites. To elucidate the role of SNAP-25 in muscle function in more detail, contractility and neuromuscular transmission were studied in a mutant mouse model termed coloboma. The coloboma mutation results from a contiguous deletion of 1-2 centiMorgans on chromosome 2, which includes the entire SNAP-25 locus and three other identified genes. Homozygotes do not survive beyond gestation day 6; heterozygotes (Cm/+) have a normal life-span but express reduced levels of SNAP-25 mRNA and protein in the brain. The consequences of the Cm/+ mutation on twitch and tetanic tension, quantal release of neurotransmitter and spinal motoneuron expression of SNAP-25 were examined in the present study. Contrary to expectations, Cm/+ mice exhibited no alteration in twitch tension and generated normal tetanic tension even at the highest frequency examined (800 Hz). Microelectrode recordings revealed that MEPP amplitude and frequency were both within control limits. The ventral spinal cord of Cm/+ mice showed no deficiency in SNAP-25 content and immunohistochemical examination of nerve terminals in Cm/+ mice disclosed that SNAP-25 levels and distribution were similar to those of control mice. It is concluded that spinal motor neurons up-regulate SNAP-25 to preserve vital neuromuscular function.

[Screening for colorectal cancer by endoscopy: rectosigmoidoscopy or coloscopy?]

Screening for colorectal cancer is almost uniformly recommended for average-risk asymptomatic persons aged 50 years and older and it may substantially reduce its relative mortality. However, consensus is lacking about the type of screening test. Flexible sigmoidoscopy followed by colonoscopy in the presence of adenoma(s), detect 70% of the neoplasms and should be recommended for adults aged 50 years and older. Colonoscopy with polypectomy may ultimately become the preferred strategy after 60 years and certainly in the presence of alarm signs and personal or familial risks for colorectal cancer.

Nodular regenerative hyperplasia of the liver. A review of 14 cases

BACKGROUND/AIMS

Nodular regenerative hyperplasia of the liver, is a noncirrhotic liver disease, characterized by nodules in the hepatic parenchyma, which clinically presents primarily with manifestations of portal hypertension. The aims of this study are i) to review the clinical, histological and diagnostic aspects of 14 documented cases of NRHL, and ii) to assess the evolution and management of this condition in the cases reviewed.

METHODOLOGY

The diagnosis of nodular regenerative hyperplasia of the liver was based on liver biopsy in all cases. Imaging studies (ultrasonography, computed tomography scan and magnetic resonance imaging scan) were performed as part of the diagnostic evaluation. Clinical manifestations and biochemical tests were recorded at the time of diagnosis. Management and prognosis were also reviewed.

RESULTS

The most common clinical manifestations were those of portal hypertension, namely splenomegaly, esophageal varices and variceal bleeding. The histological findings were nodules in the hepatic parenchyma, the typical histologic feature of nodular regenerative hyperplasia of the liver, with mild periportal fibrosis and intraportal lymphocytic infiltration. Biochemical tests showed normal synthetic liver function, as evidenced by normal serum albumin, bilirubin and prothrombin time. Elevation of gamma-glutamyl transpeptidase and alkaline phosphatase due to cholestasis was noted. Management was directed to portal hypertension and variceal bleeding, with beta-blockers, sclerotherapy, mesenteric-caval shunt and transjugular intrahepatic portosystemic shunt with satisfactory results.

CONCLUSIONS

Nodular regenerative hyperplasia of the liver is an uncommon condition but it should be considered in patients with unexplained portal hypertension and distinguished from liver cirrhosis, in view of the differences in the natural history and prognosis. Liver biopsy confirms the diagnosis. Management is directed primarily to portal hypertension and variceal bleeding, which is the main source of mortality. Liver failure is uncommon due to satisfactory preservation of liver function.

[Individual screening for colorectal cancer: which strategy for which patient?]

Currently, more than 4,000 newly colorectal cancer are diagnosed each year in Belgium. The individual average-risk for developing colorectal cancer is about 5%. 90% of colorectal cancer occurred after the age of 50, and in 70% of the cases in patients without particular risk factors (average-risk population). Personal and/or familial history of colorectal adenoma, colorectal cancer, inflammatory bowel disease localised to the colon, familial polyposis syndrome or Hereditary Non Polyposis Colorectal Cancer (HNPCC) increase the risk of colorectal cancer. An individual appropriate screening of high-risk patients and average-risk asymptomatic patients older than 50, together with endoscopic resection of adenoma decrease the incidence and the mortality of colorectal cancer. Usual screening methods are fecal occult blood testing which is not proven to be efficient alone for individual screening (but still recommended for general population's screening), sigmoidoscopy (which has to be completed by a colonoscopy, if lesions founded), and colonoscopy. Virtual colonoscopy and genetic testing need further evaluation. Currently, colonoscopy seems to be the goldstandard method providing complete examination of the whole colon and being the most cost-effective method. Screening strategy should be decided on an individual basis considering the patient's benefit with respect to the informed consent.

Assessment of acute and chronic morphine dependence in male and female mice

The present study compared male and female mice for frequency of naloxone-precipitated jumping and naloxone ED(50) values, two common indices of physical dependence, following acute and chronic morphine administration. Both sexes displayed a positive dose-response relationship between acute morphine and naloxone doses and jumping frequency. There was a significant main effect of sex, with mean jumping frequencies greater in males. The naloxone ED(50) estimate was also fourfold lower in males, indicating greater withdrawal sensitivity than females. Jumping frequencies were similar in male and female saline-treated control mice, discounting initial sex differences as a significant factor in the unequal magnitude and sensitivity in acute morphine dependence between sexes. In contrast, males and females displayed similar mean withdrawal jumping frequencies and naloxone ED(50) values after 3 days of morphine injections. Sex difference in withdrawal jumping was also not observed when morphine treatment was increased to 7 days via daily injection or continuous subcutaneous infusion. The present study demonstrates the development of greater physical dependence in male relative to female mice following acute but not chronic morphine administration.

[Therapeutic approach to chronic hepatitis B and C in the dawn of the third millenium]

We try to illustrate the latest developments in epidemiology, pathogenesis and natural history of hepatitis B and C virus infection. Practical management of the patient with chronic B and C liver disease is presented. Universal hepatitis B vaccination should be encouraged in order to reduce to zero morbidity and mortality attributable to liver disease and its complications. Patients at risk for hepatitis B or C infection should be screened and notified about their evolutive risk and the therapeutic possibilities.

Domino hepatic transplantation using the liver from a patient with primary hyperoxaluria

BACKGROUND

We report a case of domino liver transplantation using the liver harvested from a patient who underwent a combined liver and kidney transplantation for primary hyperoxaluria (PH).

METHOD

A cadaveric liver transplantation was performed in a 19-year-old man with PH. In a second step, the PH liver harvested from the first patient was transplanted in a 69-year-old man with hepatitis C-related cirrhosis, not a candidate for a classic liver graft owing to multifocal hepatocellular carcinoma.

RESULTS

At 8 months after transplantation, the domino recipient has normal hepatic function and no signs of tumoral recurrence, but he progressively developed hyperoxalemia, hyperoxaluria, and renal insufficiency.

CONCLUSION

Regarding the favorable postoperative clinical evolution, domino liver transplantations using livers from PH patients may represent a new opportunity for marginal candidates for liver transplantation. However, the progressive renal insufficiency expected in such domino recipients should limit this procedure to selected cases.

Nucleic acid supercoiling as a means for ionic switching of DNA--nanoparticle networks

Oligomeric nanoparticle networks, generated by the self-assembly of bis-biotinylated double-stranded DNA fragments and streptavidin, have been studied by scanning force microscopy (SFM). SFM imaging revealed the presence within the networks of irregular thick DNA molecules, which were often associated with distinct, Y-shaped structural elements. Closer analysis revealed that the Y structures are formed by condensation (thickening and shortening) of two DNA fragments, most likely through the supercoiling of two DNA molecules bound to adjacent binding sites of the streptavidin particle. The frequency of supercoiling was found to be dependent on the ionic strength applied during the immobilization of the oligomeric networks on mica surfaces. Potential applications of the structural changes as a means for constructing ion-dependent molecular switches in nanomaterials are discussed.

Hepatic myelopathy after splenorenal shunting: report of one case and review of the literature

Hepatic myelopathy is a rare complication of cirrhosis, usually associated with surgical or spontaneous porto-systemic shunts. Its pathophysiology is unknown. It is characterized by a motor involvement of the lower limbs without clinical sensory abnormality, leading to spastic paraparesis. These neurological features are related to a symmetric loss of myelin in the lateral corticospinal tracts. Usefulness of liver transplantation in this setting is not yet determined. We describe here the case of a 29-year-old male who presented with progressive spastic paraparesis of the lower limbs 3 years after a spleno-renal shunt.

Childhood experiences and adult behavior in a group of women with pain accounted for by psychological factors and a group recovered from major depression

OBJECTIVE

In this study twenty-four women with pain accounted for by psychological factors (DSM-IV, 307.80) and twenty-four with major depression diagnosed according to DSM-III-R were compared to study the relationship between pain and depression.

METHOD

They were examined by a semi-structured, tape-recorded interview to study their childhood experiences and adult behavior. The interviews were rated by two independent and blind raters. Interrater correlation (Cohen-Kappa) varied between good and close agreement.

RESULTS

Of childhood experiences, "brutality between parents," "brutality toward child," and "sexual abuse" were often found in both groups and were more strongly represented in these than in comparison groups of former studies. As adults, the pain group had experienced more serious illness (p = 0.037) and surgery (p = 0.014). The depression group more often had a history of depression (15/24 vs. 4/24; p = 0.001). The pain group spoke negatively of its physicians (p = 0.001), was more hostile during the interview (p = 0.041), was less convinced of the benefit of the hospital stay (p = 0.029), felt less self-responsible, and was more pessimistic (p = 0.013). The pain patients also provoked negative emotions in the raters, whereas the latter's reaction to the depression group was compassion and interest (p = 0.0005) (Pearson's chi2 and Fisher's exact tests).

CONCLUSIONS

The results show that negative childhood experiences are prominent and similar in patients with pain accounted for by psychological factors and in patients after major depression. Adult behavior, however, is very different.

Persistence of botulinum neurotoxin A demonstrated by sequential administration of serotypes A and E in rat EDL muscle

Botulinum neurotoxin serotypes A (BoNT/A) and E (BoNT/E) inhibit neurotransmitter release from peripheral cholinergic nerve terminals by cleaving different sites on SNAP-25, a protein involved in synaptic vesicle docking and exocytosis. Since recovery from BoNT/A is protracted, but reversal of BoNT/E intoxication is relatively rapid, it was of interest to determine whether sequential exposure to BoNT/A and BoNT/E could provide insight into the factors responsible for persistence of BoNT action. Extensor digitorum longus (EDL) muscles from rats were injected locally with 5 mouse LD(50) units of BoNT/A or 20 mouse LD(50) units of BoNT/E; these doses were selected to produce total paralysis of EDL muscles within 48 hr. Additional groups of rats were injected sequentially with either BoNT/A followed 48 h later by BoNT/E or with BoNT/E followed 48 h later by BoNT/A. Muscle tensions were elicited in situ in response to supramaximal stimulation of the peroneal nerve to monitor recovery from BoNT intoxication. Tensions returned to 53% and 94% of control, respectively, 7 and 15 days after injection of BoNT/E. In contrast, tensions in muscles injected with BoNT/A returned to only 2% and 12% of control at these time points. Preparations injected sequentially with BoNT/A followed by BoNT/E or with BoNT/E followed by BoNT/A exhibited slow recovery times resembling those recorded in the presence of BoNT/A alone. Pronounced atrophy of the EDL muscle was observed in rats injected with BoNT/A or in those receiving serotype combinations in either sequence, whereas no loss of muscle mass was observed in animals treated with BoNT/E alone. Data suggesting that BoNT/E can enter BoNT/A-treated preparations was obtained by findings that 3,4-diaminopyridine, which readily reversed muscle paralysis after BoNT/A exposure, lost this ability within 1 h of BoNT/E addition. Evidence that BoNT/E was able to cleave SNAP-25 at its characteristic site during sequential neurotoxin exposure was demonstrated by western blot analysis of cultured primary cortical neurons. Since the sequential exposure studies indicate that recovery from BoNT intoxication is lengthened by exposure to serotype A, but not shortened by exposure to serotype E, the duration of BoNT/A intoxication appears to be determined predominantly by the intracellular stability of catalytically active BoNT/A light chain.

Long-term terlipressin administration improves renal function in cirrhotic patients with type 1 hepatorenal syndrome: a pilot study

BACKGROUND

Hepatorenal syndrome (HRS) is a severe complication of liver cirrhosis. Recently, ornipressin, a potent splanchnic vasoconstrictor, was reported to improve renal function in patients with HRS. However, this treatment is associated with a high incidence of vascular complications. Terlipressin is thought to be as effective as ornipressin with less systemic complications.

AIMS

To evaluate the effectiveness and safety of terlipressin administration in cirrhotic patients with type 1 HRS.

PATIENTS

Twelve consecutive patients fulfilling HRS criteria of the International Ascites Club were included in the study. Median plasma creatinine and sodium, urine volume and sodium before treatment were 3.4 mg% (2.5-4.0); 127 mEq/l (124-130), 500 ml/24 h (100-1031) and 7 mEq/24 h (1-17).

METHODS

Terlipressin was administered i.v. 2 mg bid in 8 patients and tid in 4 others for at least one week and up to 2 months.

RESULTS

After one week of treatment median plasma creatinine decreased to 1.8 mg% (1.3-2.1) together with an increase in urine volume, sodium excretion, creatinine and free-water clearance. Three patients underwent successful liver transplantation with a near normal renal function after 34, 36 and 111 days. The 9 other patients died during follow-up (4 from sepsis, 2 from digestive bleeding and 3 from liver failure). No ischaemic complications were encountered during the treatment.

CONCLUSIONS

Long-term terlipressin administration is safe and effective to control type 1 HRS. However, it does not cure the underlying disease and therefore, may only be considered as a bridge to a definitive treatment as liver transplantation.

Cefdinir vs. amoxicillin/clavulanic acid in the treatment of suppurative acute otitis media in children

An investigator-blinded, randomized, multicenter study was conducted to compare the efficacy and safety of cefdinir and amoxicillin/ clavulanate (amoxicillin/CA) in the treatment of pediatric patients with acute suppurative otitis media. Patients 6 months to 12 years of age were randomized in a 1:1:1 ratio to receive cefdinir 14 mg/kg once-daily, cefdinir 7 mg/kg b.i.d., or amoxicillin/CA 13.3 mg/kg t.i.d. Test-of-cure was determined 11 to 16 days posttherapy. Of the 752 patients who entered the study, 665 (88%) completed treatment and 595 (79%) were evaluable. Response rates in the three treatment groups were similar. Overall rates of adverse events were statistically lower in the cefdinir once-daily group than in the amoxicillin/CA group. Diarrhea was the most common adverse event in all treatment groups. Cefdinir given either once-daily or twice-daily is a safe and effective treatment for pediatric patients with acute suppurative otitis media.

Preparation, characterization, and the crystal structure of the inhibitor ZK-807834 (CI-1031) complexed with factor Xa

Factor Xa plays a critical role in the formation of blood clots. This serine protease catalyzes the conversion of prothrombin to thrombin, the first joint step that links the intrinsic and extrinsic coagulation pathways. There is considerable interest in the development of factor Xa inhibitors for the intervention in thrombic diseases. This paper presents the structure of the inhibitor ZK-807834, also known as CI-1031, bound to factor Xa and provides the details of the protein purification and crystallization. Results from mass spectrometry indicate that the factor Xa underwent autolysis during crystallization and the first EGF-like domain was cleaved from the protein. The crystal structure of the complex shows that the amidine of ZK-807834 forms a salt bridge with Asp189 in the S1 pocket and the basic imidazoline fits snugly into the S4 site. The central pyridine ring provides a fairly rigid linker between these groups. This rigidity helps minimize entropic losses during binding. In addition, the structure reveals new interactions that were not found in the previous factor Xa/inhibitor complexes. ZK-807834 forms a strong hydrogen bond between an ionized 2-hydroxy group and Ser195 of factor Xa. There is also an aromatic ring-stacking interaction between the inhibitor and Trp215 in the S4 pocket. These interactions contribute to both the potency of this compound (K(I) = 0.11 nM) and the >2500-fold selectivity against homologous serine proteases such as trypsin.

Bone metastases from thyroid carcinoma: a histopathologic study with clinical correlates

CONTEXT

Only limited information exists on the pathologic aspects of thyroid carcinomas with bone metastases, most large studies having concentrated mainly on their clinical features.

OBJECTIVE

To study in detail the morphologic features of thyroid carcinomas with skeletal metastases.

DESIGN

Seventy-nine cases of thyroid carcinoma with bone metastases treated at Memorial Sloan-Kettering Cancer Center, New York, NY, between 1964 and 1998 were investigated, with emphasis on the pathology of the primary and/or metastatic tumors and comparison of the morphologic features of the tumors at both the sites, wherever possible. The tumors were also compared for various clinical parameters.

RESULTS

The cohort consisted of 22 papillary, 17 follicular, 16 insular, 10 anaplastic, 9 Hürthle cell, and 5 medullary carcinomas. Of these cases, 68% had poorly differentiated or undifferentiated features in the primary and/or metastatic tumors. The metastatic tumors were better differentiated than the primary in one third of the cases (6 of 18). Only one case showed a less differentiated metastasis. The overall 5- and 10-year survival probabilities after the bone metastases were 29% and 13%, respectively (Kaplan-Meier method). Although both the tumor type and differentiation seemed to affect survivals after bone metastasis (P =.007 and.012, respectively) (log-rank test), this was primarily due to the much worse prognosis in the cases of anaplastic and medullary carcinoma. Cases of Hürthle cell carcinoma showed the longest median survival. There was no significant difference in survival among patients up to or older than 45 years at the time of metastases (P =.31).

CONCLUSIONS

Most thyroid carcinomas with bone metastases are of papillary type, and most have poorly differentiated or undifferentiated features. The influence of the microscopic tumor type and tumor differentiation on survival after bone metastasis primarily appears to be due to the much worse prognosis among anaplastic and medullary carcinomas. Age at diagnosis of bone metastases does not influence survivals.

Antagonism of botulinum toxin A-mediated muscle paralysis by 3, 4-diaminopyridine delivered via osmotic minipumps

The ability of 3,4-diaminopyridine (3,4-DAP) to antagonize muscle paralysis following local injection of botulinum neurotoxin A (BoNT/A) complex was evaluated in the in situ rat extensor digitorum longus (EDL) preparation. The minipumps were implanted 6 h prior to BoNT/A administration and delivered their contents over a 7-day period producing a steady plasma 3,4-DAP concentration of 27-29 microM. In the absence of 3,4-DAP, a local injection of five mouse LD(50) units of BoNT/A led to total paralysis of EDL muscles within 24 h of application. Recovery from paralysis was slow, remaining at <30% of control 14 days after toxin injection. 3,4-DAP delivery by osmotic minipumps antagonized the actions of BoNT/A on neuromuscular transmission. Seven days after the onset of 3,4-DAP infusion, indirectly elicited twitch and tetanic tensions in BoNT/A-injected EDL muscles were 72.4 and 46.9% of control, respectively. In the absence of 3,4-DAP, twitch and tetanic tensions were only 5.4 and 15. 1% of control. The benefits conferred by 3,4-DAP treatment were not maintained after minipumps were removed. Seven days after cessation of 3,4-DAP infusion, twitch and tetanic tensions were not significantly different from those observed in muscles receiving BoNT/A alone. It is concluded that 3,4-DAP may be useful for treatment of BoNT/A-induced muscle paralysis, but sustained delivery of the drug would be required for the entire period of BoNT intoxication to maintain muscle function.

Sex differences in thermoregulation after acute and chronic morphine administration in mice

Sex differences in thermoregulation have been reported following acute morphine administration in rats only. This study assessed whether male and female mice also differ in thermoregulatory responses following acute and chronic morphine administration. Females displayed significantly higher baseline colorectal temperature and greater morphine (24mg/kg, s.c.) hypothermia (2. 5-fold) on day 1. Two additional days of morphine treatment did not alter baseline temperature readings on Day 4 in either sex, but significantly reduced the morphine hypothermia relative to Day 1 in a sex-dependent manner. Whereas the morphine hypothermia was completely abolished in males, significant hypothermia was still observed in females. Acute and chronic saline injections had no effect on colorectal temperature. The data demonstrate sex differences in the thermoregulatory responses to acute and chronic morphine administration in mice.

Surface composition of spray-dried particles of bovine serum albumin/trehalose/surfactant

PURPOSE

To characterize via electron spectroscopy for chemical analysis (ESCA) the surface of spray-dried particles of trehalose plus a protein (bovine serum albumin). Additionally, to show how and why the addition of a surfactant reduces protein adsorption, and by this mechanism could reduce protein instability during spray-drying.

METHODS

Aqueous solutions of trehalose plus bovine serum albumin (bSA) were spray-dried with increasing concentrations of surfactant. The surface composition of the dried particles was examined using ESCA.

RESULTS

The presence of bSA, trehalose, and surfactant could be detected quantitatively in the particle surface. In the absence of surfactant the bSA had a large surface excess concentration (determined via its N atoms). Increasing concentration of polysorbate 80 reduced the surface excess of bSA in a concentration-dependent manner. At high polysorbate 80 concentration (5 mg/ml) the bSA could no longer be detected in solid surface. Using sodium dodecyl sulfate it was shown that the reduction in surface concentration of the protein is accompanied by a simultaneous increase in surface concentration of the surfactant. Neither surfactant fully covers the surface at the point of complete protein exclusion.

CONCLUSIONS

ESCA provides a direct, quantitative measure of the surface composition of spray-dried trehalose/protein/surfactant particles. Surfactant reduces protein adsorption at the water/air-interface. This appears to be a result of complex formation with the surfactant within the bulk spray solution.

Modified genetic algorithm resolves ambiguous NOE restraints and reduces unsightly NOE violations

In an ideal world, every NOE cross peak would have a unique assignment. However, the interpretation of NOE peaks is frequently complicated by overlapping resonances. In theory, ambiguous assignments could be resolved by performing separate structure calculations with each possible interpretation. Unfortunately, this would require an astronomical amount of computing time. A modified genetic algorithm has been developed that efficiently resolves hundreds of ambiguous restraints in parallel. Each NOE assignment becomes a gene that can be passed on to a new generation. New individuals are constructed by making a constraint lists from a subset of the genes. The constraint lists are then tested for self-consistency by using molecular dynamics to generate new structures for each list. To a first-degree approximation, there is enough information retained in each list to determine the global fold of the protein. Self-consistent constraint lists receive higher scores and their genes (or NOEs) stand a better chance of surviving into the next generation. The process selects NOEs that are consistent with the global fold. Under normal conditions, the program converges in 3 to 8 generations using 70 structures per generation. The final constraints are self-consistent and contain almost no residual NOE violations.