A case with glucagonoma syndrome--heterogeneity of glucagon and insulin

The heterogeneity of glucagon and insulin in plasma and tissue extracts from a 57-year-old female with glucagonoma syndrome with surgically and autopsy verified islet-cell tumors was studied by Bio-Gel P-10 filtration. The preoperative plasma immunoreactive glucagon (IRG) level was 20.2 ng/ml, and plasma glucagon-like immunoreactivity(GLI) 25.8 ng/ml. The column chromatography of the preoperative plasma revealed three or four IRG components and four GLI components. Among these, peak II, the large glucagon immunoreactivity (LGI) peak, considered a candidate for proglucagon, was prominent, along with peak III. The resected metastatic liver tumor contained an enormous amount of IRG and an appreciable amount of immunoreactive insulin (IRI), indicating that the elevated plasma IRG was mainly of tumor origin. The IRG pattern of the tumor tissue extract revealed a small quantity of IRG in peaks I and II, and a large amount in peak III; control pancreatic tissue extract manifested a similar elution pattern. The IRI elution pattern of the tumor tissue extract revealed two major IRI peaks which migrated close to the elution volume of cytochrome C and insulin, respectively. This is a quite different pattern from the control pancreatic tissue extract in which the RI peak was localized in the elution volume of the insulin. We conclude that the present metastatic liver tumor produced not only enormous amounts of glucagon but heterogeneous peptides which contained immunological insulin determinants within their.     

Nutritional and metabolic studies in humans with 1,3-butanediol.

Three studies of the role of 1,3-butanediol (BD) in human nutrition are described. Isocaloric substitution of BD for starch in the diets of volunteers caused less negative nitrogen balance. Ingestion of urea also decreased negative nitrogen balance, and the effect of BD plus urea in the diets seemed to be additive. No effects were detected on many blood parameters measured during and after the study, except that BD feeding decreased blood glucose significantly. 1,3-Butanediol was shown to be a nontoxic metabolite providing a source of calories for human nutrition. In a second study, ingestion of BD was shown to cause slight increases in serum insulin and growth hormone concentrations in the fasting state. We next studied the effects of prior ingestion of BD on serum insulin, growth hormone, glucose, and lipids during glucose tolerance tests. No significant differences in these parameters were noted when prior ingestion of sucrose or an isocaloric quantity of BD were compared. Possible mechanisms whereby ingestion of BD spared nitrogen and caused decreased blood glucose are discussed.     

A simplified method for metabolic studies in conscious swine

Reliable short-term blood access in conscious swine was provided by implanting multiple silastic catheters. Catheters were inserted into the aorta, hepatic vein, portal vein, and inferior vena cava through a midline laparotomy incision. Multiple catheters also were placed into the external jugular vein through a separate cervical incision. Catheter patency rates for blood withdrawal on the sixth post-operative day were: arterial 100%, hepatic 91%, portal 86%, inferior vena cava 71%. No animal had major wound or catheter infection on the seventh post-operative day. The methods described allow metabolic studies, including measurements of splanchnic blood flow, to be carried out either acutely or for up to at least 7 days post-operatively.     

Adapting immunity with subunit vaccines: case studies with group A Streptococcus and malaria

Although vaccines have widely been regarded as the most cost-effective way to improve public health, for some organisms new technological advances in vaccine design and delivery, incurring additional developmental costs, will be essential. These organisms are typically those for which natural immunity is either slow to develop or does not develop at all. Clearly, such organisms have evolved strategies to evade immune responses and innovative approaches will be required to induce a type of immune response which is both different to that which develops naturally and is effective. This article describes some approaches to develop vaccines for two such organisms (malaria parasites and Streptococcus pyogenes (group A Streptococcus)) that are associated with widespread mortality and morbidity, mostly in the poorest countries of the world. At this stage, the challenges are primarily scientific, but if these hurdles are surmounted then the challenges will become financial ones--developing much needed vaccines for people least able to afford them.     

A case with combined rare inborn metabolic disorders: Congenital adrenal hyperplasia and ornithine transcarbamylase deficiency

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is a common autosomal recessive disorder. Ornithine transcarbamylase (OTC) deficiency is the most common urea cycle disorder and demonstrates X-linked inheritance. In female OTC deficiency, phenotypes are variable according to X-inactivation patterns. These disorders develop separately, and their co-morbidity is extremely rare. We report one girl with CAH showing recurrent hyperammonemia and hepatitis after 2 years-of-age due to additional OTC deficiency.     

Endocytosis by human platelets: metabolic and freeze-fracture studies

The mechanism by which platelets endocytose or release particulate or soluble substances is poorly understood. Engulfed materials enter the open canalicular system (OCS) by a process akin to phagocytosis, but fusion of platelet granules with the OCS is rarely observed. Secretion of granule contents, a concomitant of the "release reaction" which occurs during platelet aggregation, does not take place by extrusion at the surface membrane as is true for other secretory cells. Some substances may be secreted without obvious granule loss. To examine whether structural properties of the platelet membrane could account for this unusual behavior, thin section and freeze-fracture analyses were performed on platelets which had undergone endocytosis under a variety of experimental conditions. After freeze-cleavage, most of the intramembranous particles (IMP) remain associated with the outer leaflet of the platelet plasma membrane. The sites where the OCS reaches the surface membrane are marked by pits on the cytoplasmic leaflet (P face) and by complementary protrusions on the outer leaflet (E face) of the membrane. Endocytosis of small particles and solutes takes place via these structures. This process is not energy dependent but arrested at 4 degrees C. Distension of the OCS does not appear to affect the size or number of the pits. On the other hand, large particles are taken up by membrane invagination without redistribution of IMP's and independent of the pits. This process is sensitive to metabolic inhibition. Thus, the studies have demonstrated the existence of two different pathways for platelet endocytosis which are postulated to be also involved in secretion. The selective release of substances contained in different granules may be related to the "inside-out" structure of the plasma and OCS membranes.     

Generalized indicator plate for genetic, metabolic, and taxonomic studies with microorganisms.

We have developed an indicator plate that works well for diverse types of substrates and microorganisms. The plates are inexpensive and easy to prepare. The essential components are agar, buffer, growth-supporting nutrients, a test substrate, and 2,3,5-triphenyl tetrazolium chloride (TTC). Using various strains of Salmonella typhimurium and Escherichia coli, we have studied and defined the contribution of each component to the satisfactory function of the plate. Colonies capable of catabolizing the test substrate reduce TTC and produce a deep red formazan, whereas colonies failing to catabolize the substrate remain uncoloured. Those with intermediate rates of catabolism differ in rate and/or extent of color formation. In all cases the color is stable because TTC reduction is essentially irreversible. Since the mode of action of these plates is fairly well understood, alternative formulations can be devised to meet specific needs. The general applicability of this TTC indicator system makes it an extremely useful tool in microbial genetics, metabolism, and taxonomy.     

Generalized indicator plate for genetic, metabolic, and taxonomic studies with microorganisms.

We have developed an indicator plate that works well for diverse types of substrates and microorganisms. The plates are inexpensive and easy to prepare. The essential components are agar, buffer, growth-supporting nutrients, a test substrate, and 2,3,5-triphenyl tetrazolium chloride (TTC). Using various strains of Salmonella typhimurium and Escherichia coli, we have studied and defined the contribution of each component to the satisfactory function of the plate. Colonies capable of catabolizing the test substrate reduce TTC and produce a deep red formazan, whereas colonies failing to catabolize the substrate remain uncoloured. Those with intermediate rates of catabolism differ in rate and/or extent of color formation. In all cases the color is stable because TTC reduction is essentially irreversible. Since the mode of action of these plates is fairly well understood, alternative formulations can be devised to meet specific needs. The general applicability of this TTC indicator system makes it an extremely useful tool in microbial genetics, metabolism, and taxonomy.