Interaction of neurotensin with prostaglandin E2 and prostaglandin synthesis inhibitors: effects on colonic temperature in mice

Neurotensin (NT) administered intracisternally (i.c.) to adult mice produced a marked hypothermia while prostaglandin E₂, administered by the same route, produced hyperthermia. When administered concurrently the effects of the two substances were neutralized. The prostaglandin synthesis inhibitors, indomethacin and acetylsalicylic acid, were injected subcutaneously 30 min prior to i.c. administered NT and/or thyrotropin-releasing hormone (TRH). Both inhibitors failed to potentiate the hypothermia induced by NT or alter its antagonism by TRH in mice kept at 26°C. When mice were kept at 6°C, pretreatment with indomethacin, but not acetylsalicylic acid, potentiated NT-induced hypothermia and prevented its antagonism by TRH. Because indomethacin inhibits synthesis of prostaglandins within the central nervous system (CNS) as well as in peripheral organs while acetylsalicylic acid acts only in the periphery, it appears that NT-induced hypothermia in a cold environment is enhanced by a reduction of prostaglandins in the CNS.     

Interactions among coexisting larval Odonata: an in situ experiment using small enclosures

Field experiments using small replicated enclosures focused on interactions between larval populations of Epitheca cynosura and Ladona deplanata (Odonata: Anisoptera) — two species that emerge in early spring. The presence of Epitheca reduced the total biomass of Ladona, but Ladona had no significant effect on Epitheca. These early-emerging species reduced the biomass of small instars of late-emerging Anisoptera which colonized enclosures during the experiments; and the late-emerging Anisoptera seem to have inhibited colonization by Zygoptera larvae. Results are consistent with the importance of predatory (cannibalism or mutual predation) interactions in this community.     

The latex agglutination test versus counterimmunoelectrophoresis for rapid diagnosis of bacterial meningitis

A modified latex agglutination (LA) test was compared with Gram-staining and counterimmunoelectrophoresis (CIE) for the rapid detection in the cerebrospinal fluid (CSF) of antigen to Haemophilus influenzae type b, Neisseria meningitidis groups A, B and C, Escherichia coli K1, Streptococcus pneumoniae and group B streptococci, seven frequent causes of bacterial meningitis in children. Of 50 CSF samples from patients with culture-proven bacterial meningitis 90% were correctly shown by the LA test to contain antigen of the responsible organism. Gram-staining revealed organisms in 80% of 45 of these samples. In 75% of the 40 samples that were of sufficient volume for CIE, positive results for the appropriate antigen were obtained. The concentration of antigen detected in the CSF by the LA test varied from undetectable to 800 000 ng/ml. Patients with a high concentration (more than 2000 ng/ml or a positive result at dilutions of CSF over 1/8) were significantly more likely to have a poor response to therapy (two died and two had persistent pleocytosis or bacteria in the CSF) than patients with a lower concentration (4/16 v. 0/18, P < 0.05). After appropriate therapy was begun the concentration of antigen fell dramatically, but measurable amounts of antigen persisted in the CSF for up to 6 days. The LA test detected bacterial antigen at concentrations 2 to 70 times below the lower limit detected by CIE. In seven additional patients who had received antibiotics before lumbar puncture was performed the LA test detected antigen from meningitis-causing bacteria even though cultures of the CSF were sterile. In another 145 patients who did not have meningitis the results of the LA test were negative. The LA test, done as described in this article, is easier to perform than CIE and should be a useful addition to the diagnostic tests carried out on the CSF of any patient suspected of having meningitis.     

Processing and amino acid sequence analysis of the mouse mammary tumor virus env gene product.

The envelope proteins of mouse mammary tumor virus (MMTV) are synthesized from a subgenomic 24S mRNA as a 75,000-dalton glycosylated precursor polyprotein which is eventually processed to the mature glycoproteins gp52 and gp36. In vivo synthesis of this env precursor in the presence of the core glycosylation inhibitor tunicamycin yielded a precursor of approximately 61,000 daltons (P61env). However, a 67,000-dalton protein (P67env) was obtained from cell-free translation with the MMTV 24S mRNA as the template. To determine whether the portion of the protein cleaved from P67env to give P61env was removed from the NH2-terminal end of P67env and as such would represent a leader sequence, the NH2-terminal amino acid sequence of the terminal peptide gp52 was determined. Glutamic acid, and not methionine, was found to be the amino-terminal residue of gp52, indicating that the cleaved portion was derived from the NH2-terminal end of P67env. The NH2-terminal amino acid sequences of gp52's from endogenous and exogenous C3H MMTVs were determined though 46 residues and found to be identical. However, amino acid composition and type-specific gp52 radioimmunoassays from MMTVs grown in heterologous cells indicated primary structure differences between gp52's of the two viruses. The nucleic acid sequence of cloned MMTV DNA fragments (J. Majors and H. E. Varmus, personal communication) in conjunction with the NH2-terminal sequence of gp52 allowed localization of the env gene in the MMTV genome. Nucleotides coding for the NH2 terminus of gp52 begin approximately 0.8 kilobase to the 3' side of the single EcoRI cleavage site. Localization of the env gene at that point agrees with the proposed gene order -gag-pol-env- and also allows sufficient coding potential for the glycoprotein precursor without extending into the long terminal repeat.     

Retention of human skin fibroblast fatty acid modifications during maintenance culture

Summary The fatty acid composition of cultured human skin fibroblasts was modified by adding either oleic or linoleic acid to the growth medium. After the cultures became confluent, they were washed and transferred to different maintenance media in order to determine the stability of the various fatty acyl modifications. Some changes in fatty acid composition occurred under all conditions. When the maintenance medium was supplemented with fatty acid, the cellular neutral lipid and phospholipid fatty acyl composition were altered markedly within 16 to 24 hr. If no supplemental fatty acid was available during the maintenance period, however, the modified fatty acyl compositions were sufficiently retained so that appreciable differences between the cells enriched with oleate and linoleate persisted for at least 48 to 72 hr. This considerable degree of stability occurred when either 10% delipidized fetal bovine serum or 10% fetal bovine serum containing its inherent lipids were present in the maintenance medium. Although the triglyceride content of the fatty acid-modified cells was quite labile, neither the cholesterol nor phospholipid content changed appreciably during culture in any of the maintenance media. Since the fatty acid compositional differences persisted during several days of maintenance under certain conditions, these modified cultures appear to be a useful experimental system for assessing the effect of lipid structure on fairly long-term cellular functions. This work was supported by Arteriosclerosis Specialized Center of Research Grant HL14230 from the National Heart, Lung and Blood Institute, National Institutes of Health.     

A history of theories of acquired immunity

Alloimmune mouse spleen cells are capable of carrying out nonspecific cell-mediated cytolysis of syngeneic target cells when incubated in the presence of lectins such as Con A or PHA (lectin-dependent cell-mediated cytotoxicity). In the present study plant lectins from a variety of sources were examined for their ability to participate in alloimmune-LDCC. Reactivity was then compared to mitogenic activity and the ability to activate cytotoxic effector cells in vitro. Of the lectins tested only those reported to be T-cell mitogens were capable of participating in alloimmune-LDCC. Agglutinating but nonmitogenic lectins (e.g., WGA) or mitogens such as LPS or PWM failed to yield positive LDCC. Of the T-cell mitogens demonstrating positive reactivity in the alloimmune-LDCC assay, only a portion were able to generate cytolytic activity when incubated with normal spleen cells in vitro (Con A, GPA, lentil). Crude PHA, purified erythroagglutinin, or leukagglutinin failed to generate cytotoxic effector cells in this system even though these were mitogenic and demonstrated positive alloimmune-LDCC. The results suggest that T-cell mitogens interact with cytotoxic effector cells in a manner which specifically triggers cytolysis. The relationship of this interaction to other lymphocyte-lectin interactions is discussed.     

A general method for permeabilizing monolayer and suspension cultured animal cells

A wide variety of animal cells have been successfully permeabilized to non-penetrating molecules, using lysolecithin. The sizes of molecules that can enter the cells can be controlled by varying the concentration of lysolecithin. The cells become permeable to small molecules and maintain viability following treatment with low lysolecithin concentrations. At higher concentrations the cells become permeable to proteins but do not retain viability. Lysolecithin permeabilization should permit many studies of the effects of non-penetrating compounds on cellular processes.     

ABLATIVE TECHNIQUES FOR SURGICAL TREATMENT OF PAROXYSMAL TACHYCARDIA

In this report, the collaborative efforts of cardiologists and surgeons to provide optimal treatment of patients with rhythm disturbances are discussed, along with definitive advances in new surgical techniques to relieve supraventricular tachycardia and paroxysmal ventricular tachycardia. Some of the techniques described are destined to find a permanent place in the surgeon's armamentarium.     

Histochemical Demonstration of Enzyme Activities in Plastic and Paraffin Embedded Tissue Sections

Histochemical staining for enzymes is usually performed on frozen sections. This report lists the longer incubation times required to demonstrate esterase, acid phosphatase, β-galactosidase, and cytochrome oxidase in plastic embedded and routine paraffin embedded tissues. The sections embedded in plastic, i.e. water soluble methacrylate (Polyscience's JB-4) and cut at 2 μm, were far superior to frozen Sections and paraffin embedded sections both in tissue detail and in the localization of the histochemical reaction product.