Klinefelter syndrome

BACKGROUND: To determine the maximum tolerable dose (MTD) and therapeutic activity of MTHF-modulated FU using two different administration schedules of the antimetabolite (bolus vs. two-hour infusion), the present randomized study using a 'pick-the-winner' design was undertaken in patients with advanced colorectal cancer. PATIENTS AND METHODS: Eighty-two patients with previously untreated advanced measurable colorectal cancer were randomly assigned to treatment with MTHF (100 mg/m2 days 1-5 i.v. bolus) plus FU (400 mg/m2 days 1-5) given either as i.v. bolus injection or as a two-hour infusion every four weeks. In the absence of dose-limiting toxicity (DLT, defined as > or = WHO grade 3 hematotoxicity and/or > or = WHO grade 2 nonhematologic side effects) and evidence of progressive disease, the FU dose was escalated by 50 mg/m2/day during each subsequent cycle until the individual maximum tolerable dose (MTD) was reached. RESULTS: Forty patients were randomized to the FU bolus arm and 42 patients to the FU two-hour infusion arm. The median MTD was 475 mg/m2/day (95% CI: 450-500) in the FU bolus arm with stomatitis +/- diarrhea being the most common DLT. Gastrointestinal side effects were also dose-limiting in the two-hour infusion arm; however, the median MTD was 600 mg/m2/day (95% CI: 568-632). Myelosuppression was more pronounced in the FU bolus arm than in the two-hour infusion arm. The overall response rates were 27.5% (95% CI: 15-44%; 1 CR and 10 PR) for patients treated in the bolus arm and 14.5% (95% CI: 5-28%; 1 CR and 5 PR) for those treated in the two-hour infusion arm. Analogous to recorded response, median time to progression (8.5 vs. 6.25) and overall survival time (14.0 vs. 11.0) tended to be superior in the FU bolus arm. CONCLUSIONS: The observed differences in tolerable drug dose and toxicity between the two treatment arms might be explained by the administration schedule-dependent clinical pharmacokinetics of FU and/or the difference in extent of biochemical modulation of the antimetabolite through MTHF. The fact that the two regimens were not equitoxic probably also helps to explain the favourable response activity noted in the MTHF/FU bolus arm. Whether MTHF is as effective as leucovorin for biochemical modulation of FU remains to be determined in a randomized trial, for which we would recommend its combined use with bolus FU ('winner arm') using a starting dose of 400 mg/m2/day x5.     

Analysis of the intracellular localization and assembly of Ro ribonucleoprotein particles by microinjection into Xenopus laevis oocytes

Xenopus laevis oocytes have been used to determine the intracellular localization of components of Ro ribonucleoprotein particles (Ro RNPs) and to study the assembly of these RNA-protein complexes. Microinjection of the protein components of human Ro RNPs, i.e., La, Ro60, and Ro52, in X. laevis oocytes showed that all three proteins are able to enter the nucleus, albeit with different efficiencies. In contrast, the RNA components of human Ro RNPs (the Y RNAs) accumulate in the X. laevis cytoplasm upon injection. Localization studies performed at low temperatures indicated that both nuclear import of Ro RNP proteins and nuclear export of Y RNAs are mediated by active transport mechanisms. Immunoprecipitation experiments using monospecific anti-La and anti-Ro60 antibodies showed that the X. laevis La and Ro60 homologues were cross-reactive with the respective antibodies and that both X. laevis proteins were able to interact with human Y1 RNA. Further analyses indicated that: (a) association of X. laevis La and Ro60 with Y RNAs most likely takes place in the nucleus; (b) once formed, Ro RNPs are rapidly exported out of the nucleus; and (c) the association with La is lost during or shortly after nuclear export.     

Energetics of triosephosphate isomerase: the nature of the proton transfer between the catalytic base and solvent water

The isomerization of specifically deuterium-labeled [1(R)-2H5dihydroxyacetone phosphate to D-glyceraldehyde 3-phosphate, catalyzed by the enzyme triosephosphate isomerase, has been studied. It is shown that the extent of transfer of the 2H label from the substrate to the product D-glyceraldehyde 3-phosphate is (after complete reaction) the same as that of the corresponding transfer of 3H. The absence of an isotope effect shows that the exchange process of the tstopically labeled enzyme carboxyl group, -COOL H2O leads to -COOH + LOH, does not tnvolve a rate-limiting transition state in which L is the flight. Possible modes for the nature of the ionization of -COOL in 1H2O are discussed.     

Aromatic analogs of arcaine inhibit MK-801 binding to the NMDA receptor

Aromatic analogs of arcaine were shown to have inhibitory effects on the binding of the channel blocking drug [3H]MK-801 to the NMDA receptor complex. The most potent compound of the series was an N,N'-bis(propyl)guanidinium which inhibited [3H]MK-801 binding with an IC50 of 0.58 microM and an IC50 of 12.17 microM upon addition of 100 microM spermidine. The increase in IC50 upon addition of spermidine suggests competitive antagonism between the inhibitor and spermidine at the arcaine-sensitive polyamine site of the NMDA receptor complex.     

Development and validation of transient isotachophoretic capillary zone electrophoresis for determination of peptides

Although capillary zone electrophoresis (CZE) is known for its high resolution power and low mass detection limits, the concentration detection limits are rather poor when ultraviolet absorbance detection is used. To overcome this limitation, several on-column transient isotachophoresis (tITP) protocols have been developed and validated for the determination of both cationic and anionic model peptides, separately. Using this preconcentration method, up to 72% of the capillary can be filled with sample solution, without any loss in resolution. Thus, without any modification of the hardware set-up, the sensitivity is increased about two orders of magnitude. For the model cationic peptides (gonadorelin, angiotensin II) good linearity and reproducibility is observed in the 20 to 100 ng/mL concentration range. For the anionic peptides (N-t-Boc-Pentagastrin and two related peptides), a tITP method was developed using a dynamically coated capillary. The coating was prepared by adding Fluorad FC-135 to the leading electrolyte buffer. In this way a positively charged bilayer was formed on the inside of the capillary, producing an electroosmotic flow towards the outlet using reversed polarity conditions. In this way, acceptable analysis times were achieved. Using the developed tITP method, up to 72% of the capillary can be filled with sample solution as well. The anionic peptides are separated even better than when using CZE conditions. Linearity and reproducibility in the 20-100 ng/mL range proved to be excellent.     

GABA receptors in the dorsal motor nucleus of the vagus influence feline lower esophageal sphincter and gastric function

Gamma-aminobutyric acid (GABA) antagonist (bicuculline methiodide, BIC; picrotoxin, PIC) or agonist (muscimol, MUS) microinjections were made into the dorsal motor nucleus of the vagus nerve (DMV), and effects on lower esophageal sphincter pressure (LESP), gastric motility, and gastric acid secretion were determined in chloralose-anesthetized cats. Right or left DMV sites were microinjected with BIC, PIC, MUS, or isotonic tonic saline (140 nl) through a glass micropipette having a tip diameter of 15-21 microns. Esophageal body, LESP, and gastric fundic pressures were measured manometrically. Circular smooth muscle contractions of the antrum and pylorus were recorded with strain-gauge force transducers. Gastric acid secretion was measured every 15 min through a gastric cannula and titrated to pH 7.0. DMV microinjection sites were verified histologically. Direct BIC microinjections (0.275 or 0.550 nmol) into the DMV primarily produced a decrease in LESP (71% of all sites tested), with mean LESP changing from 23.2 +/- 1.7 mmHg to 3.7 +/- 0.7 mmHg (p < 0.01). Tonic LESP increases and phasic LESP contractile activity occurred less frequently. BIC-induced LESP responses were abolished by vagotomy or by microinjections of MUS (0.5 to 10 nmol) into the DMV. Direct PIC microinjection (0.232 nmol) into the DMV produced a pattern of responses similar to those observed with BIC (which were also abolished by vagotomy or by MUS microinjections into the DMV). The antrum and pylorus were also responsive to DMV microinjections of both GABA antagonists. Microinjections of BIC or PIC into the DMV produced increases in gastric circular muscle activity that occurred less frequently than LESP effects, but also were eliminated by vagotomy. The high (0.550 nmol) dose of BIC increased gastric motility significantly more often than the low dose of BIC (p < 0.05). In addition, BIC (0.550 nmol) microinjections into the DMV increased gastric secretory volume (from 0.6 +/- 0.2 to 6.0 +/- 2.5 ml/15 min; p < 0.01) and total titratible acid (from 34.4 +/- 8.9 to 86.0 +/- 19.1 mEq/15 min; p < 0.01), and decreased gastric pH (from 4.63 +/- 0.44 to 3.50 +/- 0.49; p < 0.05). Vagotomy also eliminated the gastric secretory effects of DMV BIC. Direct microinjections of MUS into the DMV also blocked BIC- or PIC-induced changes in gastric motility and/or gastric acid secretion. Isotonic saline microinjected into the DMV did not increase basal or decrease stimulated gastric esophageal motility or gastric secretion. These data indicate that LESP, gastric motility, and gastric secretion are influenced by a tonic DMV inhibition mediated by GABAA receptor stimulation of the DMV. Because disinhibition of these receptors clearly activates the upper gut, future work should focus on identifying the nuclei providing this synaptic input to the DMV that might be involved in the functional regulation of upper gut motor and secretory function.     

Incidences of problematic organisms on petrifilm aerobic count plates used to enumerate selected meat and dairy products

Petrifilm aerobic count plates are similar to or better than conventional pour plates. Petrifilm has its problems, however; some microorganisms can liquefy the Petrifilm gel and others do not produce the necessary color change with the indicator dye used. Petrifilm aerobic count plates were compared with the pour plates for determining the incidence and identification of problematic organisms in 329 meat and dairy products. Petrifilm plates produced higher mean counts with better repeatability than did pour plates. There was also close correlation between methods with coefficients of 0.97 to 1.0. Bacillus subtilis, Bacillus licheniformis, and a group D Streptococcus liquefied Petrifilm gels in 17.4% of the samples tested: dairy products accounted for 16.0%, and meats accounted for the remaining 1.4%. Liquefaction hindered enumeration in 3.2% of the Petrifilm plates used. Streptococcus viridans was not detectable on Petrifilm plates after the recommend incubation period, and this organism occurred in 0.3% of the Petrifilm plates used. These results indicate that Petrifilm plates would be unsuitable for samples with large numbers of these organisms. Knowledge of the contaminating flora may be an asset when utilizing Petrifilm aerobic count plates for the enumeration of microbes in food.     

Spectrum of clinicopathologic manifestations of arrhythmogenic right ventricular cardiomyopathy/dysplasia: a multicenter study

OBJECTIVES: The aim of the present investigation was to redefine the clinicopathologic profile of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC), with special reference to disease progression and left ventricular (LV) involvement. BACKGROUND: Long-term follow-up data from clinical studies indicate that ARVC is a progressive heart muscle disease that with time may lead to more diffuse right ventricular (RV) involvement and LV abnormalities and culminate in heart failure. METHODS: Forty-two patients (27 male, 15 female; 9 to 65 years old, mean [+/-SD] age 29.6 +/- 18) from six collaborative medical centers, with a pathologic diagnosis of ARVC at autopsy or heart transplantation, and with the whole heart available, were studied according to a specific clinicomorphologic protocol. RESULTS: Thirty-four patients died suddenly (16 during effort); 4 underwent heart transplantation; 2 died as a result of advanced heart failure; and 2 died of other causes. Sudden death was the first sign of disease in 12 patients; the other 30 had palpitations, with syncope in 11, heart failure in 8 and stroke in 3. Twenty-seven patients experienced ventricular arrhythmias (ventricular tachycardia in 17), and 5 received a pacemaker. Ten patients had isolated RV involvement (group A); the remaining 32 (76%) also had fibrofatty LV involvement that was observed histologically only in 15 (group B) and histologically and macroscopically in 17 (group C). Patients in group C were significantly older than those in groups A and B (39 +/- 15 years vs. 20 +/- 8.8 and 25 +/- 9.7 years, respectively), had significantly longer clinical follow-up (9.3 +/- 7.3 years vs. 1.2 +/- 2.1 and 3.4 +/- 2.2 years, respectively) and developed heart failure significantly more often (47% vs. 0 and 0, respectively). Patients in groups B and C had warning symptoms (80% and 87%, respectively, vs. 30%) and clinical ventricular arrhythmias (73% and 82%, respectively, vs. 20%) significantly more often than patients in group A. Hearts from patients in group C weighed significantly more than those from patients in groups A and B (500 +/- 150 g vs. 328 +/- 40 and 380 +/- 95 g, respectively), whereas hearts from both group B and C patients had severe RV thinning (87% and 71%, respectively, vs. 20%) and inflammatory infiltrates (73% and 88%, respectively, vs. 30%) significantly more often than those from group A patients. CONCLUSIONS: LV involvement was found in 76% of hearts with ARVC, was age dependent and was associated with clinical arrhythmic events, more severe cardiomegaly, inflammatory infiltrates and heart failure. ARVC can no longer be regarded as an isolated disease of the right ventricle.