Symposium on diarrhea. 5. Postoperative diarrhea.

Under normal circumstances many physiologic mechanisms prevent diarrhea. The most important are the normal processes of gastric emptying, digestion and absorption, the functioning of the ileocecal valve and elimination of bacteria from the small bowel. A surgical procedure may disrupt any of these mechanisms or may unmask a previously asymptomatic disorder that now requires appropriate treatment. Treatment of diarrhea related to surgery may be directed toward the diarrhea itself with such agents as tranquilizers and opiates but if these are not soon effective any disrupted functions must be analysed and specific measures taken to correct or compensate for these disruptions. The most useful measures in appropriate cases are the prevention of the dumping syndrome and the administration of pancreatic enzymes, cholestyramine, hydrophilic stool thickeners and broad-spectrum antibiotics. These measures may be ineffective or inadequate and surgical revision may be necessary.     

Symposium on diarrhea. 6. Infectious diarrhea.

Diarrhea may be primarily infectious in origin. Causes can be conveniently classified according to the etiologic agent, which may be viral, chlamydial, bacterial, protozoal, helminthic or fungal. The most common type of infectious diarrhea in Canada is viral. Bacterial infection, particularly staphylococcal and salmonellal, also is relatively common.     

Minimally invasive surgery. Neurosurgery.

The introduction of minimally invasive techniques has greatly improved results for intracranial neurosurgery. Stereotaxy and improved imaging techniques have reduced surgical trauma by allowing surgeons to plan the least damaging route to operative sites and by increasing surgical precision. Stereotaxy has also allowed brain biopsies to be taken from sites such as the brain stem, which were rarely sampled before because free hand biopsy was so dangerous. Brain tumours can now be treated by interstitial radiotherapy--stereotactic insertion of catheters into the lesion for loading of radioactive iodine--or radiosurgery--focusing of intense beams of radiation on lesions without needing surgical incisions. Endoscopic neurosurgery can be used to reach cavities such as the ventricular system or cystic tumours. With interventional neuroradiology fine catheters can be introduced into most vessels in the cranium for embolisation or dilatation. The development of augmentative functional neurosurgery means that movement disorders, epilepsy, and intractable pain can be treated with implanted neurostimulating electrodes. Future developments will probably include frameless stereotaxy, when the rigid attachment of stereotactic apparatus to the patient''s head can be dispensed with, and at least partial automation of procedures such brain biopsy.     

Lymphocyte-activating factor. I. Generation and physicochemical characterization.

Lipopolysaccharide-activated murine peritoneal macrophages elaborate lymphocyte-activating factor (LAF) which is mitogenic for murine thymocytes. A method of LAF production is presented that permits the generation of a relatively homogeneous molecular species. LAF has an isoelectric point of 4.8 (range 4.7-4.9). The m.w. was determined by using several physical techniques. The apparent sedimentation coefficient (S20,w) was determined to be 2.0S by sucrose gradient ultracentrifugation. The Stokes (molecular) radius was determined by gel filtration on Sephadex G-75 to be 22 A (range 21.5 to 22.5); the calculated diffusion coefficient (D20,w) was 9.7 X 10(-7) cm2/sec (range 9.5 X 10(-7) to 9.9 X 10(-7). The buoyant density of LAF is 1.30 g/cm3 (range 1.27 to 1.33) as determined by CsCl isopycnic ultracentrifugation; the partial specific volume was estimated to be 0.72 (range 0.70 to 0.74). From these data, the m.w. was calculated to be 18,000 daltons (range 16,400 to 19,600) with the Svedberg equation. The frictional ratio was calculated to be 1.25.     

On the nature of P.P.L.O.

Summary In a number of strains of the three species of P.P.L.O. of human origin coccoid elements have been observed, which are Gram positive or Gram variable and of very small size (<0.5 μ). They are able to grow in pure culture on the surface of nutrient agar in very small colonies. Although they have bacterial characteristics, they could not be identified as known bacteria. Agglutination tests are in favour of a serological relationship between the coccoid elements and P.P.L.O. The suggestion that these elements might be an outside contamination is made unlikely by several observations. The supposition that P.P.L.O.s are L forms of these coccoid elements should be considered further.     

Multipoint gene mapping using seriation. I. General methods.

Initial and accurate inference of locus order and estimates of interlocus distances and interference can be obtained using seriation techniques. The analysis requires a matrix of recombination values that can be estimated by standard pairwise linkage analysis. This allows combination of results from individual investigators without reanalysis of basic pedigree material. Seriation can be performed without the use of a computer.     

Symposium on diarrhea. 3. Investigation of chronic diarrhea.

The practical approach to the investigation of diarrhea must be logical and based on anatomic considerations. The site of the underlying disorder may be determined by the clinical picture, and the logic of investigation will be influenced by the history. Important specific investigation in a case of colonic diarrhea include a careful rectal examination, stool inspection, sigmoidoscopy, rectal biopsy and barium enema study. Colonoscopy has been used, but its role has yet to be defined. In a case of small-bowel steatorrhea or diarrhea quantitative chemical estimation of the daily output of stool fat is useful, and to this investigation is added a small-bowel radiograph series and, if the radiographic findings are abnormal, small-bowel biopsy. Other investigations for small-bowel disease may include the breath test with carbon-14-labelled glycocholic acid, the lactose tolerance test, duodenal aspiration for giardiasis, analysis of serum immunoglobulins and, on occasion, isolation of vasoactive intestinal polypeptide hormone (which may aid the diagnosis of functioning tumours of the pancreas or small bowel). Investigations for pancreatic steatorrhea include abdominal radiography, performance of the secretin test and testing of the response to pancreatic replacement therapy. In some patients it may be useful to use endoscopic retrograde cholangiopancreatography to differentiate pancreatic carcinoma and chronic pancreatitis.     

1H n.m.r. study of geletin gels

Proton spin-lattice and spin-spin relaxation times have been measured in the gelatin-water system during gelatin at various concentrations and quenching temperatures. The spin-spin relaxation time is shown to be a good parameter for following the kinetics of gelation and can be related to the amount of helices measured by polarimetry. The results are analysed within the framework of the Zimmerman-Brittin theory.     

The A.M.A. Session

The use of liquid nitrogen for the removal of warts has advantages over electrocautery in certain circumstances. Although the incidence of recurrences after liquid nitrogen is higher than after cautery, it causes considerably less scarring. It is most useful in dealing with peri-ungual and multiple warts. The technique is simple and a supply of liquid nitrogen can be kept on hand in the office at relatively low cost.     

Q. & A. on C. P. S

Encephalitis is a challenging public health problem in Kern County and in the San Joaquin Valley area. During the last ten years the authors have studied the epidemiology of encephalitides due to arthropod-borne viruses and the methods used in the differential dignosis of these conditions. To incriminate a virus it is necessary to demonstrate a rise in antibody titer in the blood over a period of seven to fourteen days, the first specimen to be taken as soon as possible after onset of symptoms. A variety of tests may be necessary in some cases. Among the patients included in this presentation the greater number of those with encephalitis and also of those with poliomyelitis were under 30 years of age. The age range was five weeks to 49 years. The median annual mortality rate was 4.3 deaths per 100 cases for poliomyelitis and 3.9 for encephalitis. The greatest incidence occurred during the summer months.The clinical manifestations usually observed in encephalitis are described, but it is emphasized that wide variations and even completely atypical clinical phenomena are encountered. Four representative cases are reported and treatment is discussed. Vaccination and vector control are considered as the most promising means of combating the disease.     

Mitochondrial GTP-AMP phosphotransferase. 2. Kinetic and equilibrium dialysis studies.

Kinetic and equilibrium dialysis substrate binding studies have been done to investigate the properties of mitochondrial GTP-AMP phosphotransferase. The results show that the enzyme has a specific requirement for divalent metal ions, namely Mg2+, Mn2+ or Ca2+ (Ca2+ is active only in the forward direction, the direction of formation of ADP). The reaction rate depends upon the ratio [Mg2+]:[substrate] rather than on the metal ion concentration alone. The enzymatic activity is influenced by NaCl (or KCl) and optimum pH occurs at 11.5 and 9.5 for guanosine and inosine nucleotides respectively. Examination of binding of substrates to the enzyme showed that there is one binding site (GTP site) for MgGTP, GTP, MgGDP or GDP per molecule of enzyme, with dissociation constants of 4.5, 4.4, 3.0, 2.2 micron respectively and one binding site (AMP site) for AMP, ADP or ATP per molecule of enzyme with dissociation constants of 20.9, 33.4 and 33.4 microns respectively. Since, within the limitations of equilibrium dialysis used in the present studies, AMP binding to one site of the enzyme could be detected only when GDP or GTP is present, the mechanism of the forward reaction may be assumed to be nearly ordered. For the reverse reaction there is no requirement of order of binding of the two nucleotides and so the mechanism of reaction may be assumed to be random.     

The A.M.A. Session

The use of liquid nitrogen for the removal of warts has advantages over electrocautery in certain circumstances. Although the incidence of recurrences after liquid nitrogen is higher than after cautery, it causes considerably less scarring. It is most useful in dealing with peri-ungual and multiple warts.The technique is simple and a supply of liquid nitrogen can be kept on hand in the office at relatively low cost.     

Minimally invasive surgery. Future developments.

The rapid development of minimally invasive surgery means that there will be fundamental changes in interventional treatment. Technological advances will allow new minimally invasive procedures to be developed. Application of robotics will allow some procedures to be done automatically, and coupling of slave robotic instruments with virtual reality images will allow surgeons to perform operations by remote control. Miniature motors and instruments designed by microengineering could be introduced into body cavities to perform operations that are currently impossible. New materials will allow changes in instrument construction, such as use of memory metals to make heat activated scissors or forceps. With the reduced trauma associated with minimally invasive surgery, fewer operations will require long hospital stays. Traditional surgical wards will become largely redundant, and hospitals will need to cope with increased through-put of patients. Operating theatres will have to be equipped with complex high technology equipment, and hospital staff will need to be trained to manage it. Conventional nursing care will be carried out more in the community. Many traditional specialties will be merged, and surgical training will need fundamental revision to ensure that surgeons are competent to carry out the new procedures.     

土圞儿属和旋花豆属(豆科)的孢粉学研究

在扫描电子显微镜下,对豆科土儿属(Ap ios)和旋花豆属(Coch lianthus)7个种植物的花粉进行了观察.结果表明,2个属的花粉均为三孔沟,形状为三角球形或球形.土儿属的花粉可划分为2种类型:肉色土儿(A.carnea)的花粉外壁为典型的网状纹饰,其它种的花粉外壁较光滑,具颗粒状或短条纹状纹饰,研究结果不支持土儿属下亚属的划分;肉色土儿花粉外壁的网状纹饰式样可能反映了其在土儿属中处在较进化的位置.土儿属东亚分布种的花粉类型较为多样,原始和进化2种类型并存,表明东亚可能是土儿属的起源地和演化中心.旋花豆属的花粉特征和肉色土儿相似,说明两者之间的亲缘关系可能较近.     

For debate . . . Individual contributions to multiauthor papers.

The curricula vitae of four candidates for a professorial appointment at Athens University were examined to estimate the actual contribution of each candidate to the papers of which he was a coauthor. A total of 879 research papers by the four candidates were analysed in terms of the number of authors, the sequence of names, and the year of publication. The four authors presented 364, 349, 96, and 70 papers. If an equal contribution of all coauthors is assumed, the actual number of papers (all papers divided by the number of authors), is about 106, 83, 28, and 26, respectively, so that the rank of the four candidates did not change. On the assumption that the contribution was related to the candidate''s position in the order of the coauthors'' names, the numbers of papers were corrected to 84, 95, 26, 33 using one statistical method and to 88, 94, 28, 31 using another. These assumptions may not be valid, however, especially as the last author may be more important than the intermediate ones. It is suggested that the journals require authors to state their specific contribution to a paper, such as original idea, planning, collecting data, writing up, etc.     

Benzylidene acetal structural elucidation by N.M.R. Spectroscopy: Application of carbon-13. N.M.R.-Spectral parameters

The ₁₃C-n.m.r. spectra of 19 2-phenyl-1,3-dioxolane, -1,3-dioxane and -1,3-dioxopane derivatives were examined and it was found that both the ₁₃C-n.m.r. chemical shift for the acetal carbon atom and the one-bond coupling constant between the acetal carbon atom and the acetal proton had values that could be used to distinguish between acetals having different ring sizes. In addition, the presence of axial substituents at positions 4 or 6 in substituted 2-phenyl-1,3-dioxane rings and 4 or 7 in substituted 2-phenyl-1,3-dioxepane rings could be readily detected. The structures of a number of carbohydrate examples were determined by using these two parameters and also the chemical shift of the acetal proton from ₁H-n.m.r. spectra. The use of all three parameters made assignment of benzylidene acetal ring-size unambiguous.     

88MHz 113Cd-n.m.r. studies of native rat liver metallothioneins.

Preparations of microvilli from kidneys of BALB/c mice contain an alkaline metallo-endopeptidase, meprin (metallo-endopeptidase from renal tissue). Certain genealogically related inbred mice are markedly deficient in meprin activity. The meprin-deficient strains (CBA/J and C3H/HeJ) exhibit normal levels of other brush-border enzymes: alkaline phosphatase, aminopeptidase M and another proteinase, a phosphoramidon-sensitive neutral endopeptidase. Meprin deficiency cannot be attributed to a shift in pH optimum and is unlikely to be due to the presence of endogenous inhibitors.     

Review: ethidium fluorescence assays. Part 1. Physicochemical studies.

DNA and RNA can be assayed rapidly and very sensitively by exploiting the enhanced fluorescence of ethidium intercalated into duplex regions. By assaying at different pHs and introducing a heating/cooling cycle, a great many physicochemical aspects of DNA and RNA can be studied avoiding the use of radiolabels, and often giving information not otherwise readily obtainable. Studies are described on duplex DNA which involve measurement of extinction coefficients, cross-linking by chemicals, Cot curve analysis as well as estimation of drug-DNA binding constants. The assays can be adapted to investigate multi-stranded nucleic acid structures. The use of covalently closed circular DNA also allows rapid and extremely sensitive measurements of nicking caused by irradiation or drugs.     

Considerations in the U.S. Environmental Protection Agency's testing approach for mutagenicity.

OPP: This paper provides the rationale and support for the decisions the OPP will make in requiring and reviewing mutagenicity information. The regulatory requirement for mutagenicity testing to support a pesticide registration is found in the 40 CFR Part 158. The guidance as to the specific mutagenicity testing to be performed is found in the OPP's Pesticide Assessment Guidelines, Subdivision F, Hazard Evaluation: Human and Domestic Animals (referred to as the Subdivision F guideline). A revised Subdivision F guideline has been presented that becomes the current guidance for submitters of mutagenicity data to the OPP. The decision to revise the guideline was the result of close examination of the version published in 1982 and the desire to update the guidance based on developments since then and current state-of-the-science. After undergoing Agency and public scrutiny, the revised guideline is to be published in 1991. The revised guideline consists of an initial battery of tests (the Salmonella assay, an in vitro mammalian gene mutation assay and an in vivo cytogenetics assay which may be either a bone marrow assay for chromosomal aberrations or for micronuclei formation) that should provide an adequate initial assessment of the potential mutagenicity of a chemical. Follow-up testing to clarify results from the initial testing may be necessary. After this information as well as all other relevant information is obtained, a weight-of-evidence decision will be made about the possible mutagenicity concern a chemical may present. Testing to pursue qualitative and/or quantitative evidence for assessing heritable risk in relation to human beings will then be considered if a mutagenicity concern exists. This testing may range from tests for evidence of gonadal exposure to dominant lethal testing to quantitative tests such as the specific locus and heritable translocation assays. The mutagenicity assessment will be performed in accordance with the Agency's Mutagenicity Risk Assessment Guidelines. The mutagenicity data would also be used in the weight-of-evidence consideration for the potential carcinogenicity of a chemical in accordance with the Agency's Carcinogen Risk Assessment Guidelines. In instances where there are triggers for carcinogenicity testing, mutagenicity data may be used as one of the triggers after a consideration of available information. It is felt that the revised Subdivision F guideline will provide appropriate, and more specific, guidance concerning the OPP approach to mutagenicity testing for the registration of a pesticide. It also provides a clearer understanding of how the OPP will proceed with its evaluation and decision making concerning the potential heritable effects of a test chemical.(ABSTRACT TRUNCATED AT 400 WORDS)