The effect of indomethacin on cerebral blood flow and oxygen consumption in the rat at normal and increased carbon dioxide tensions

The effect of the fatty acid cyclo-oxygenase inhibitor indomethacin on cerebral blood flow (CBF) and the metabolic rate for oxygen (CMRO₂) was studied in paralyzed and artificially ventilated rats. In normocapnic animals, the drug (10 mg·kg^-1i. v.) reduced CBF to 50% of control without a measurable effect on CMRO₂. During hypercapnia (Pa_CO2 70–80 mmHg) the increase in CBF was reduced by about 80% but CMRO₂ remained unchanged. Autoradiographic evaluation of local CBF in 20 brain structures indicated that the reduction in CBF was relatively uniform throughout the brain. Dose response curves showed that an effect on CBF was evident already at an indomethacin dose of 1 mg·kg^-1 and maximal effects were obtained with 3–5 mg·kg^-1. Following i. v. injection of the drug reduction in CBF was observed already after 10 s and the full response occurred after 1–2 min. It is concluded that metabolites of arachidonic acid, possibly mainly prostacyclin, are powerful modulators of normal cerebrovascular tone, and help to mediate the CBF response to increased CO₂ tensions. However, since indomethacin does not modify the circulatory response in other conditions with increased CBF these substances do not qualify as general coupling factors controlling CBF in physiological or pathological states.     

Measurement of Ventilation and Respiratory Mechanics during Continuous Positive Airway Pressure (CPAP) Treatment in Infants

ABSTRACT. A new method has been evaluated for measuring ventilation and lung mechanics in spontaneously breathing infants by means of a face chamber. Airway flow is measured with a pneumotachograph inserted between the face chamber and a stable pressure source. Oesophageal pressure is measured via a water-filled oesophageal catheter. The method is suitable for use in conjunction with continuous positive airway pressure (CPAP) treatment in neonatal intensive care. A flat frequency response curve up to 15 Hz for the two measuring systems (i.e., airway flow and oesophageal pressure), and a time shift between the two respective signals of less than 2 msec are prerequisites for correct evaluation of respiratory mechanics. In preterm infants with chest distortion, the inhomogeneity of pleural pressure affects the significance of resistance and compliance values, as calculated from oesophageal pressure. Supra-diaphragmatic pressure variations reflect the resistive and elastic load on the diaphragm exerted by the lungs and thorax. Thus, oesophageal pressure is still useful in studies of respiratory mechanics in preterm infants.     

The Normal Development of the Lymphoid Mass in the Golden Hamster and its Relationship to the Effects of Thymectomy

A study of lymphoid organ sections and imprints of normal hamsters fromfetal to adult state revealed a sequential pattern of organ structure and growth.The thymus developed an adult structure by 1 week, maximum size at 6 weeks.The mesenteric lymph node had an adult structure by 4 weeks, the spleen by 6weeks, with an accelerated growth of both organs between 6 to 8 weeks. Thegrowth and development of the peripheral lymphoid organs appears to beunder thymic control until the attainment of a "critical peripheral lymphoidmass." This appears capable of functioning independently of thymic control.Thymectomy is effective in producing lymphoid atrophy with resultant immunosuppression and wasting disease only if performed prior to the attainmentof the "critical peripheral lymphoid mass."

Submitted on February 6, 1964 Accepted on July 26, 1964     

Mechanisms of Pancreatic B-Cell Degeneration during the Course of Insulin-dependent Diabetes Mellitus

ABSTRACT. This paper presents a review of different mechanisms possibly responsible for the degeneration of the pancreatic B-cell in insulin-dependent diabetes mellitus. The genetic dependence probably located in the HLA DR-locus of the sixth chromosome and its role in an autoimmune reaction against antigenieally altered pancreatic B-cells is discussed. The actions of alloxan and streptozotacin in the induction of experimental diabetes, as models for postulated human B-cytotoxins, are described.     

Erythropoiesis: Correlations Between Iron Status Markers During Normal Pregnancy in Women with and without Iron Supplementation

The aim was to evaluate relationships between iron status markers (haemoglobin, erythrocyte indices, serum iron, serum transferrin, serum transferrin saturation, serum ferritin) in normal pregnancy. Iron status markers were measured at 4-week-intervals during pregnancy and postpartum in 120 healthy women; 62 had daily treatment with tablets containing 66 mg ferrous iron, 58 were treated with placebo. Placebo-treated: Ferritin displayed positive correlations with transferrin saturation during 2nd and 3rd trimester. There were positive correlations between ferritin, erythrocyte MCV and MCH during 2nd and 3rd trimester and postpartum. Prior to delivery and postpartum, ferritin demonstrated positive correlations with haemoglobin. Transferrin saturation showed positive correlations with MCV, MCH and MCHC during 2nd and 3rd trimester and postpartum. Transferrin saturation displayed positive correlations with haemoglobin prior to delivery and postpartum. Iron-treated: In general, there were no correlations between iron status markers. Positive correlations appeared postpartum between ferritin, transferrin saturation and MCHC but not with haemoglobin. Transferrin saturation showed a positive correlation with MCH postpartum, but not with haemoglobin. Conclusion: The patterns of relationships in placebo-treated women were consistent with iron deficient erythropoiesis.     

Erythropoiesis: Short Report: Translation of Analysis Results between Serum Ferritin Assays, Ferritin RIA AmershamTM and Abbott AxSYMTM Ferritin

The serum ferritin assays, Ferritin RIA Amersham(TM) and Abbott AxSYM(TM) Ferritin were compared in order to translate values from one assay to the other. Serum ferritin was analysed with both assays in 102 samples. Logarithmic transformation of the results was performed in order to stabilize the variance. The relationship between the untransformed values was most exactly expressed by a proportionality: AxSYM Ferritin = 0.873 * RIA Ferritin. Due to this proportionality, the numerical difference between the assays increases with the ferritin concentration, although the percentage difference between the assays remains constant.