Locations and amplitudes of the extrema of the sinx/x function

This paper addresses the calculation of the extrema of the sin x/x function. First the Newton-Raphson method is used, which allows us to obtain the extrema locations very fast through the use of a recursion formula. Then a second approach is proposed, which gives the extrema locations and the extrema amplitudes in the form of series expansions. Simple, accurate algebraic expressions are derived.     

Novel NMDA antagonists: replacement of the pyridinium ring of 6,11-ethanobenzo[b]quinolizinium cations with heteroisoquinolinium cations

Replacement of the pyridinium ring of 6,11-ethanobenzo[b]quinolizinium cations with thiazolium (4a and 4b) and N-methylimidazolium (4c and 4d) resulted in equipotent compounds in the [3H]TCP binding assay. The corresponding N-methyl-1,2,4-triazolium analogs were less potent in this assay. The thiazolium derivative 4b, with a Ki = 2.9 nM, is being evaluated as a possible neuroprotective N-methyl-D-aspartic acid (NMDA) antagonist.     

Ventilatory response to severe acute hypoxia in guinea-pigs and rats with high hemoglobin-oxygen affinity induced by cyanate

Laparoscopic pelvic lymph node dissection has been applied as a minimally invasive staging technique for men with prostate cancer. This procedure has been shown to shorten markedly postoperative hospitalization, decrease analgesic requirements and shorten convalescence period compared to open pelvic node dissection. However, the laparoscopic procedure takes longer to perform and many disposable instruments are used, thus increasing the cost. We determine the overall cost of laparoscopic versus open pelvic lymph node dissection. Between January 1989 and April 1992, 61 men underwent only staging pelvic lymph node dissection for cancer of the prostate at a single university teaching hospital. Of these patients 11 and 50 underwent open and laparoscopic pelvic lymph node dissection, respectively. Information from the hospital business office was reorganized into preoperative, intraoperative and postoperative expenses. All individual charges were transformed up or down to the dollar amounts of the 1990 to 1991 fiscal year so as to correct for inflationary changes. Preoperative costs were not significantly different between the 2 operative approaches. Intraoperative expenses were 52% greater if laparoscopic pelvic lymph node dissection was performed and can be explained by the longer operative times and use of disposable instrumentation. However, the postoperative period lasted an average of 1.61 days following laparoscopic pelvic lymph node dissection. Postoperative nursing and analgesic requirements were significantly more for patients undergoing open pelvic lymph node dissection. The overall postoperative costs following open pelvic lymph node dissection were 280% more expensive than for the laparoscopic procedure. The overall total costs were approximately $1,250 more for laparoscopic pelvic lymph node dissection. Wages lost or earned during this period and rapid return to normal activity following laparoscopic pelvic lymph node dissection would, in our opinion, justify this additional cost.     

Analysis of the roles of antilipopolysaccharide and anti-cholera toxin immunoglobulin A (IgA) antibodies in protection against Vibrio cholerae and cholera toxin by use of monoclonal IgA antibodies in vivo

Secretory immunoglobulin A (IgA) antibodies (sIgA) directed against cholera toxin (CT) and surface components of Vibrio cholerae are associated with protection against cholera, but the relative importance of specific sIgAs in protection is unknown. A monoclonal IgA directed against the V. cholerae lipopolysaccharide (LPS), secreted into the intestines of neonatal mice bearing hybridoma tumors, was previously shown to provide protection against a lethal oral dose of 10(7) V. cholerae cells. We show here that a single oral dose of 5 to 50 micrograms of the monoclonal anti-LPS IgA, given within 2 h before V. cholerae challenge, protected neonatal mice against challenge. In contrast, an oral dose of 80 micrograms of monoclonal IgA directed against CT B subunit (CTB) failed to protect against V. cholerae challenge. A total of 80 micrograms of monoclonal anti-CTB IgA given orally protected neonatal mice from a lethal (5-micrograms) oral dose of CT. Secretion of the same anti-CTB IgA antibodies into the intestines of mice bearing IgA hybridoma backpack tumors, however, failed to protect against lethal oral doses of either CT (5 micrograms) or V. cholerae (10(7) cells). Furthermore, monoclonal anti-CTB IgA, either delivered orally or secreted onto mucosal surfaces in mice bearing hybridoma tumors, did not significantly enhance protection over that provided by oral anti-LPS IgA alone. These results demonstrate that anti-LPS sIgA is much more effective than anti-CT IgA in prevention of V. cholerae-induced diarrheal disease.     

An approach for treating the hepatobiliary disease of cystic fibrosis by somatic gene transfer

Cystic fibrosis (CF) is an inherited disease of epithelial cell ion transport that is associated with pathology in multiple organ systems, including lung, pancreas, and liver. As treatment of the pulmonary manifestations of CF has improved, management of CF liver disease has become increasingly important in adult patients. This report describes an approach for treating CF liver disease by somatic gene transfer. In situ hybridization and immunocytochemistry analysis of rat liver sections indicated that the endogenous CFTR (cystic fibrosis transmembrane conductance regulator) gene is primarily expressed in the intrahepatic biliary epithelial cells. To specifically target recombinant genes to the biliary epithelium in vivo, recombinant adenoviruses expressing lacZ or human CFTR were infused retrograde into the biliary tract through the common bile duct. Conditions were established for achieving recombinant gene expression in virtually all cells of the intrahepatic bile ducts in vivo. Expression persisted in the smaller bile ducts for the duration of the experiment, which was 21 days. These studies suggest that it may be feasible to prevent CF liver disease by genetically reconstituting CFTR expression in the biliary tract, using an approach that is clinically feasible.     

Mitochondrial DNA haplotype frequencies in natural and experimental populations of Drosophila subobscura

The evolution of Drosophila subobscura mitochondrial DNA has been studied in experimental populations, founded with flies from a natural population from Esporles (Majorca, Balearic Islands, Spain). This population, like other European ones, is characterized by the presence of two very common (>96%) mitochondrial haplotypes (called I and II) and rare and endemic haplotypes that appear at very low frequencies. There is no statistical evidence of positive Darwinian selection acting on the mitochondrial DNA variants according to Tajima's neutrality test. Two experimental populations, with one replicate each, were established with flies having a heterogeneous nuclear genetic background, which was representative of the composition of the natural population. Both populations were started with the two most frequent mitochondrial haplotypes, but at different initial frequencies. After 13 to 16 generations, haplotype II reached fixation in three cages and its frequency was 0.89 by generation 25 in the fourth cage. Random drift can be rejected as the force responsible for the observed changes in haplotype frequencies. There is not only statistical evidence of a linear trend favoring a mtDNA (haploid) fitness effect, but also of a significant nonlinear deviation that could be due to a nuclear component.     

Dependence of attenuation in a vegetation canopy on frequency andplant water content

Theory is presented to provide insight into the observation that attenuation through vegetation is proportional to vegetation water content. In this analysis, the canopy is modeled as a sparse layer of randomly oriented particles (leaves, stalks, etc.) over a flat, homogeneous ground plane (soil) and an expression is obtained for the “optical depth”. The formulas developed by Ulaby and El Rayes are used to relate this expression to the water content of the canopy. In the low frequency extreme (Rayleigh scatterers), the attenuation varies almost linearly with water content and inversely with wavelength. In contrast, in the high frequency limit, the attenuation is independent of both water content and frequency, in between, geometry dependent “resonances” occur even at the low frequency end of the microwave spectrum (e.g. L-band) making the dependence of attenuation on frequency and water content specific to canopy architecture     

Value of transcranial Doppler indices in predicting raised ICP in infantile hydrocephalus. A study with review of the literature

Cerebral hemodynamic changes in infants with progressive hydrocephalus have been studied with the transcranial Doppler (TCD) technique. Several authors have referred to the correlation between the hemodynamic changes and increased intracranial pressure (ICP). Despite conflicting conclusions on the value of pulsatility index (PI) and resistance index (RI) measurements for monitoring infantile hydrocephalus, these pulsatility indices are the most commonly used for this purpose. Although clinical signs of raised ICP are highly variable and unreliable in infants, assumptions have been made in most of the studies about the presence of elevated ICP on the basis of the patient's clinical state. Few studies have reported on actual ICP values, however, and a direct relationship between ICP and TCD changes has never been adequately demonstrated. In the present study, this relationship was investigated in long-term simultaneous TCD/ICP measurements, in an attempt to develop a noninvasive method of monitoring the effect of ICP on intracranial hemodynamics. Two groups of data sets were established. Group I consisted of pre- and postoperative (shunt implantation) TCD/ICP measurements. Group II were long-term simultaneous TCD/ICP recordings showing significant ICP variations. In most of the postoperative measurements there was a decrease in the average PI and RI values. The correlation between PI or RI and ICP in the long-term simultaneous recordings, however, was generally poor. The risk of obtaining false positive or false negative PI or RI values in short-term measurements was also demonstrated. It can be concluded from our results, besides the wide range of reference values for the Doppler indices and extracranial influences upon them, that the present Doppler indices are inadequate for monitoring the complex intracranial dynamic responses in patients with raised ICP.