Dibutyryl cAMP-induced protein changes in differentiating mouse neuroblastoma cells

Proteins from mouse neuroblastoma cells treated with dibutyryl adenosine-3',5'-monophosphate (B2cAMP) were analyzed by high resolution, two-dimensional gel electrophoresis. Quantitative changes in proteins and charge modifications of proteins apparently induced B2cAMP were detected by isoelectric focusing. Some proteins appeared to be modified and one protein was increased 7- to 8-fold in cells treated with B2cAMP. Since neuroblastoma cells differentiate when treated with B2cAMP, understanding the protein changes induced by B2cAMP may help to understand cellular differentiation in neural tissue.

Measles vaccine efficacy determined from secondary attack rates during a severe epidemic

In February, March, and April 1974, a severe epidemic of measles, with 71 cases and three deaths, occurred on the Cheyenne and Standing Rock Sioux Indian Reservations in South and North Dakota. The attack rate was 9.0 cases per 1,000 persons, and associated with the illness were 24 cases of pneumonia and ten cases of otitis media. Age-specific attack rates were highest in those under one year of age. Using secondary attack rates in persons under nine years of age who were vaccinated and unvaccinated family contacts of cases, vaccine efficacy was measured as 97.3% (95% confidence interval 80.1 to 99.9%).

The incidence and aetiology of respiratory tract infections in general practice--with emphasis on Mycoplasma pneumoniae

The incidence of respiratory tract infections in patients seeking medical advice at a community care centre (Dalby) during 1973 and 1974 was studied. About every third patient seen at this primary health station presented with signs of such infections. In the age groups less than 10, 10-19, 20-39, 40-59 and greater than or equal to 60 years, respiratory tract infections accounted for 65, 45, 32, 18 and 9% of the fotal number of diagnoses made during 1974. The aetiology of acute respiratory tract infections in a series of patients seen at this health station was studied. The series included randomly selected cases, but excluded children under seven years of age and patients presenting with signs of acute otitis media and tonsillitis. Attempts to establish the aetiology were made on the basis of the history, the clinical examination, and cultures for beta-haemolytic streptococci and Mycoplasma pneumoniae, complement foxation tests for influenza A and B, para-influenza 1, 2, and 3, adeno, cytomegalovirus and respiratory syncytial virus, and Chlamydia psittaci. Paul-Bunnell test and tests for cold agglutinins were also performed. With this test battery, an aetiological diagnosis was obtained in only 33% of the 101 patients studied. The findings suggest an infection with M.pneumoniae in 16%, with beta-haemolytic streptococci in 9%, and with viruses (adeno and para-influenza) in 7% of the patients. The present communication highlights the role of M.pneumoniae in upper respiratory infections, as few data have appeared on such infections in patients seen in general practice. The difficulty of establishing the aetiology of respiratory tract infections and the consequent treatment dilemma is discussed.

Absence of autoregulation of cerebral blood flow during halothane and enflurane anesthesia

The effects of halothane and enflurane anesthesia under conditions of normo-, hyper-, and hypocarbia on the autoregulation of cerebral blood flow (CBF) in the goat were evaluated. The goat was selected because of its unique arterial blood supply to the head and the development of a method by which CBF may be continuously measured. The study revealed that 1 MAC of halothane or enflurane anesthesia at normocarbia abolished cerebral autoregulation, CBF increasing or decreasing with increasing or decreasing peripheral blood pressure. Reduction of anesthesia to 0.5 MAC partially restored cerebral autoregulatory capability. The effect of 1 MAC and 0.5 MAC anesthesia on cerebral autoregulation of blood flow was potentiated by hypercarbia and antagonized by hypocarbia, indicating that the vascular response to blood CO2 fluctuations remained intact.

Molecular changes associated with proteolysis of bovine factor V by thrombin

Native factor V contains two major polypeptide chains, h and 1. The molecular weights determined by gel electrophoresis in the presence of sodium dodecylsulfate and dithiothreitol (125 000 and 73 000) are in reasonable agreement with those obtained by gel filtration in 5 M guanidine-HC1 (125000 and 64000). Exposure of factor V to thrombin results in cleavage of the heavier chain to an altered form with a molecular weight of 87000. The other fragment of this proteolytic reaction appears to be a carbohydrate-rich piece, which migrates abnormally slowly on gel electrophoresis conducted under denaturing and reducing conditions. Both proteolytic cleavage products remain associated with the light chain during the purification of factor V. The 87000-Mr fragment is present in samples of factor V which are isolated by immunoprecipitation of blood obtained from a single animal by venous catheter. This finding suggests that some proteolysis may occur in vivo. In contrast, the molecular weight of the light chain is unaltered after thrombin proteolysis of either purified factor V or thrombin-treated plasma.

Management of heparin therapy: Controlled prospective trial

Among 100 consecutive patients receiving heparin in therapeutic dosage, major bleeding occurred in 21, and minor bleeding in 16. Two patients died from bleeding, and two had recurrent pulmonary embolism. Major bleeding occurred in 21% when therapy was regulated with whole-blood clotting time and in 20% when heparin was given without clotting tests. In a subsequent prospective trial patients received heparin by intermittent intravenous injection with or without laboratory control according to the partial thromboplastin time or continuously by intravenous infusion. Recurrent thromboembolism occurred once in each group. Major bleeding was seven times more frequent with intermittent injection than with continuous infusion. Control with the partial thromboplastin time did not prevent major bleeding in patients receiving intermittent injections. With continuous infusion, one-fourth less heparin was required than with intermittent injections. Administration of heparin by continuous infusion appears safer than intermittent injection with or without laboratory control and is no less effective for prevention of thromboembolism.

Regulation of acetylcholinesterase in neuroblastoma cells

The specific activity of mouse neuroblastoma acetylcholinesterase (EC 3.1.1.7) increased 25-fold when the rate of cell division was restricted. The results show that acetylcholinesterase activity is regulated in neuroblastoma cells and that the regulatory mechanism is inversely related to the rate of cell division. Under the same conditions the specific activity of catechol-O-methyl transferase (EC 2.1.1.6) did not change significantly.