Effect of cholera toxin and prostaglandins on the rat choroid plexus in vitro

The present study was performed to measure the effects of cholera toxin (CT) and prostaglandins (PG) on choroid plexus cyclic AMP accumulation. Choroid plexuses, isolated from Sprague-Dawley rats, were incubated in Krebs-Ringer bicarbonate buffer containing either CT (10 microgram/ml), heat inactivated CT, prostaglandins, or appropriate controls. After a minimum incubation period of 60 min with CT, cyclic AMP accumulation (pmol/mg protein) in treated incubates (58.10 +/- 6.43, n = 6) was 4 times that in controls (14.-5 +/- 1.4, n = 6). This large increase was only seen when theophylline (10 mM) was in the incubation mixture 3--10 min prior to the end of the incubation period. The increase in cyclic AMP accumulation was dose responsive and was irreversible after 5 min of incubation. Of the 5 prostaglandins studied, only PGE2 resulted in an increase in cyclic AMP accumulation. Cyclic AMP levels were 29.64 +/- 2.5 in controls and 57.57 +/- 3.5 in plexus which had been incubated with PGE2 (20 microgram/ml) for 1 min, and this increase was dose responsive.     

Cortical Modification of an Epileptogenic Focus

The influence of cerebral cortex on penicillin-induced spikes in striate cortex was studied with the technique of hypothermic block. Direct cooling of the involved or contralateral striate cortex markedly reduced seizure activity. Significant reduction in seizure activity was also seen with cooling of ipsilateral and contralateral visual association cortex. None of the other cortical areas tested had a reproducible effect on the frequency of seizures. These findings are discussed in term of local and remote factors influencing the epileptogenic focus.     

Radiotherapy in carcinoma of the middle ear and auditory canal.

In the decade 1961 to 1970, 89 patients with epidermoid carcinoma of the middle ear or auditory canal were seen. Seventy-eight were treated with 5-year survival figures of 22 per cent for middle ear, 42 per cent for auditory canal and 31 per cent for the total group. The majority of failures occurred within 18 months of diagnosis. The author suggests that radiotherapy and surgery must be combined to improve results. Eleven patients in the series developed second primary tumours.     

Naturally occurring humoral immunity to murine mammary tumor virus (MuMTV) and MuMTV GP52 in mice with low mammary tumor incidence.

Antibodies to murine mammary tumor virus (MuMTV) were found in sera from male and female mice by means of a radiolabelled intact MuMTV precipitation assay. These antibodies were demonstrated both in strains of mice that have a high incidence of mammary tumors and transmit the highly oncogenic MuMTV via the milk (C3H) and in mice that have been foster-nursed to remove the highly oncogenic milk-borne MuMTV (C3Hf) and subsequently have a decreased mammary tumor incidence. Antibodies to MuMTV were readily demonstrated in C3H mice at 6 weeks of age, whereas only marginal antibody activity was detected in C3Hf mice of less than 15 weeks of age. Antibody levels increased with age in both strains, but in C3Hf mice the immune response was also accelerated by pregnancy. Several feral and BALB/c NIV mouse sera with high (¹²⁵I)MMTV precipitating titers also precipitated the major MuMTV envelope glycoprotein (gp52). Maximum precipitation of the (¹²⁵I)gp52 was >50% with a 20% endpoint binding titer of 1:40, whereas the same sera precipitated >80% of (¹²⁵I)MMTV with a titer of >1:2560. These naturally occurring antibodies were specific for gp52 since only MuMTV and purified MuMTV gp52 competed for binding of radiolabelled antigens by limiting dilutions of mouse sera. MuMTV gp52 was found in both C3H and C3Hf mice, predominantly in organs which had secretory functions, such as submaxillary glands and mammary tissue of females and submaxillary, coagulating, and vesicular glands and vas deferens of males. Extracts of other tissues were negative for MuMTV gp52. Neither gp52 nor naturally occurring antibodies for MuMTV were found in BALB/c or C57BL/6 mice.     

Nodular mesenteritis: Report of a case simulating carcinoma of the sigmoid colon and analysis of its histologic profile

Summary A case of nodular mesenteritis simulating a carcinoma of the sigmoid is presented. The unusual features of the case are analyzed. Emphasis is placed on the basic histologic reactions seen in nodular mesenteritis and on their possible implications. The questionable relationship to Weber-Christian disease is discussed.     

Hemoglobin solution: Is a normal [Hb] or P50 more important?

Although stroma-free hemoglobin solution (SFH) supports normal levels of oxygen consumption in baboons exchange transfused to zero hematocrit, a significant decrease occurs in the mixed venous oxygen tension ($\text{P}\text{v}\text{O}{}_2$). The hemoglobin concentration (6–8 g%) and P₅₀ (12–17 Torr) are both low in the current SFH preparations, and it is likely that they contribute to the low $\text{P}\text{v}\text{O}{}_2$ values. A multiple linear regression analysis was used to quantitate the contribution of simultaneous changes in [Hb] and P₅₀ to the observed change in $\text{P}\text{v}\text{O}{}_2$ during total exchange transfusion with SFH. During the study the average $\text{P}\text{v}\text{O}{}_2$ decreased from 51.4 to 22.4 Torr; the [Hb] fell from 11.6 to 5.1 g%; and the P₅₀ decreased from 31 to 19.5 Torr. The resulting equation was $\text{P}\text{v}\text{O}{}_2\text{= 4.0[}\text{Hb}\text{] + 0.33 P}{}_{50}\text{- 4.2}$. The equation calculates that the 6.5 g% decrease in [Hb] was responsible for a fall in $\text{P}\text{v}\text{O}{}_2$ of 26 Torr, while the fall in P₅₀ of 11.5 Torr decreased the $\text{P}\text{v}\text{O}{}_2$ only 3.8 Torr. The data suggest that an increased [Hb] should be more effective in raising $\text{P}\text{v}\text{O}{}_2$ than a higher P₅₀. Since a low $\text{P}\text{v}\text{O}{}_2$ is an indication of a reduced oxygen reserve, future efforts should attempt to achieve a hemoglobin solution with a normal [Hb].