Frequency of low molecular weight IgM in human cord blood

Thirty cord blood sera from healthy neonates and five sera from still-born infants (two with suspected infections and high IgM) were assessed for the presence of low molecular weight (LMW) IgM using two independent sensitive techniques, viz. filtration chromatography and immunoblotting. The first technique revealed this LMW moiety in 4 of 22 sera, all from healthy full-term infants, and it constituted 4-25% of the total IgM. LMW IgM was not found in any of the 30 sera using the immunoblotting technique or in 15 healthy adult sera, but was found consistently in rheumatoid sera used as positive controls.

Serological investigations in the diagnosis and management of infective endocarditis

In a retrospective study of 39 patients with infective endocarditis (IE) all had elevated concentrations of C reactive protein (CRP) at presentation, patients with the acute variety having significantly higher values than patients with the subacute variety. In addition, the majority of patients with subacute bacterial endocarditis had elevated concentrations of circulating immune complexes (CICs) and rheumatoid factor (RF), both of which were absent in all but one of nine patients with acute bacterial endocarditis. Two patients with subacute and one with acute bacterial endocarditis had low values of C3 and C4. Measurement of CRP, CICs, and RF did not distinguish between patients with and without extracardiac manifestations. Sequential analysis of patients revealed that a successful response to antimicrobial treatment was indicated by a striking and rapid decline in CRP, with less striking declines in CICs, RF, and IgM. Antibiotic failure was indicated by the persistence of high concentrations of CRP and CICs. We conclude that the measurement of C reactive protein is of some value in the diagnosis and management of infective endocarditis. A normal CRP concentration excludes this diagnosis. The measurement of CRP alone appears sufficient for monitoring most cases of infective endocarditis with the sequential measurement of rheumatoid factor and circulating immune complexes adding no useful information except where the CRP remains elevated despite treatment. In this latter instance, persisting high levels of CRP and circulating immune complexes together herald an ominous course.

In vitro production of glycosaminoglycans by retinal microvessel cells and lens epithelium

Analysis of bovine lens capsules and retinal microvessel basement membranes by cellulose acetate electrophoresis, together with treatment by specific enzymes or by nitrous acid, reveals that heparan sulfate is the only demonstrable glycosaminoglycan (GAG), consistent with the observations of most other investigators on basement membrane preparations from several different tissues. When bovine retinal microvessel pericytes or endothelial cells or bovine lens epithelial cells are grown in culture in the presence of [35S]-sulfate or [3H]-glucosamine, however, both cellulose acetate electrophoresis and gel filtration chromatography reveal that the cultured pericytes synthesize primarily chondroitin sulfate, whereas the lens epithelial cells and microvascular endothelial cells produce a mixture of GAGs consisting of approximately 60% heparan sulfate and 40% chondroitin sulfate. The chondroitin sulfate chains have an Mr of 70,000, but the Mr of the heparan sulfate chains is 10,000, based on gel filtration chromatography on Sepharose CL-6B. Hence, cell culture conditions may produce phenotypic modulation of the biosynthetic capacities of these cells for GAGs. However, the difference between the in vitro and in vivo findings may in part be explained if many of the chondroitin sulfate GAGs synthesized in vitro are cell associated and are not incorporated into the basement membrane.

Does the retinal pigment epithelium polarize the choriocapillaris?

Morphometric evaluation of choroidal capillaries from spontaneously hypertensive (SHR) rats with anatomically normal and severely dystrophic retinas reveals a marked polarization of endothelial fenestrations, endothelial cytoplasmic thickness, and endothelial cell nuclei. The mean density of fenestrations per unit endothelial length is greatest and the cytoplasmic thickness and number of nuclei is least in capillary sectors closest to the retinal pigment epithelium (RPE), with a statistically significant, continuous decrease in density of fenestrations and an increase in endothelial thickness and nuclear numbers in sectors progressively farther from the RPE. Abnormal capillaries derived from the retinal circulation and growing within the RPE also have fenestrations, but show no anatomic polarization. These results are consistent with the recently proposed hypothesis that a diffusible, trophic factor, produced by the RPE and secreted from its basal surface, modulates the structure of nearby vascular endothelial cells. However, the endothelial cells themselves probably also influence the structure of the RPE, since complex infoldings of the RPE plasma membrane, identical to those normally present in its basal surface, are also extensively present surrounding the abnormal intra-RPE capillaries.

Collagens of the retinal microvascular basement membrane and of retinal microvascular cells in vitro

We have analysed the collagens present in vascular basement membranes isolated from bovine retinal and cerebral microvessels and bovine renal glomeruli, and from the non-vascular basement membrane of bovine lens capsule. These are compared with the collagens produced by cultured bovine retinal microvascular pericytes and lens epithelial cells, and by canine retinal microvascular endothelial cells, in vitro. Biochemical and immunocytochemical analyses indicate that all of the vascular basement membrane preparations have an identical collagenous composition, consisting of the same polypeptides present in lens capsule (primarily type IV collagen), together with other polypeptides that are identified as type I, and a small amount of type III collagen. Identification of the latter is based on two-dimensional gel electrophoresis in the presence and absence of a reducing agent. Immunocytochemical studies, however, demonstrate type I, type IV and some type V collagen in the basement membranes of the isolated microvessels. The cultured microvascular cells produce predominantly type I collagen molecules, but they also produce other collagen peptides that appear to be type IV, and, at least in some experiments, small amounts of type III collagen. The biochemical identification of collagens type I and IV is confirmed by immunocytochemistry. However, results with anti-type I collagen and procollagen antibodies in cultured pericytes vary with antibodies from different sources. The quantities of the type IV peptides produced by the cultured cells also vary in different experiments.

Multiple disturbances of free fatty acid metabolism in noninsulin-dependent diabetes. Effect of oral hypoglycemic therapy

To assess the mechanisms for the elevation of free fatty acids in noninsulin-dependent diabetes, free fatty acid metabolism and lipid and carbohydrate oxidation were compared in 14 obese diabetic Pima Indians and in 13 age-, sex-, and weight-matched nondiabetics. The studies were repeated in 10 of the diabetics after 1 mo of oral hypoglycemic therapy. Fasting plasma glucose concentrations were elevated in diabetics (242 +/- 14 vs. 97 +/- 3 mg/dl, P less than 0.01) and decreased to 142 +/- 12 (P less than 0.01) after therapy. Fasting free fatty acid concentrations were elevated in diabetics (477 +/- 26 vs. 390 +/- 39 mumol/liter, P less than 0.01) and declined to normal values after therapy (336 +/- 32, P less than 0.01). Although free fatty acid transport rate was correlated with obesity (r = 0.75, P less than 0.001), the transport of free fatty acid was not higher in diabetics than in nondiabetics and did not change after therapy. On the other hand, the fractional catabolic rate for free fatty acid was significantly lower in untreated diabetics (0.55 +/- 0.04 vs. 0.71 +/- 0.06 min-1, P less than 0.05); it increased after therapy to 0.80 +/- 0.09 min-1, P less than 0.05, and was inversely correlated with fasting glucose (r = -0.52, P less than 0.01). In diabetics after therapy, lipid oxidation rates fell significantly (from 1.35 +/- 0.06 to 1.05 +/- 0.01 mg/min per kg fat-free mass, P less than 0.01), whereas carbohydrate oxidation increased (from 1.21 +/- 0.10 to 1.73 +/- 0.13 mg/min per kg fat-free mass, P less than 0.01); changes in lipid and carbohydrate oxidation were correlated (r = 0.72, P less than 0.02), and in all subjects lipid oxidation accounted for only approximately 40% of free fatty acid transport. The data suggest that in noninsulin-dependent diabetics, although free fatty acid production may be elevated because of obesity, the elevations in plasma free fatty acid concentrations are also a result of reduced removal, and fractional clearance of free fatty acid appears to be closely related to diabetic control. Furthermore, the increase in fractional clearance rate, despite a marked decrease in lipid oxidation, suggests that the clearance defect in the diabetics is due to an impairment in reesterification, which is restored after therapy.

Down syndrome and acute leukemia in children: a 10-year retrospective survey from Childrens Cancer Study Group

Review of 5406 children with acute lymphoblastic (ALL) or nonlymphoblastic leukemia (ANLL) registered with Childrens Cancer Study Group (CCSG) since 1972 identified 115 patients (2.1%) with Down syndrome. The proportion of patients with Down syndrome was the same for ALL (2.1%) and ANLL (2.1%). Patients with ALL with and without Down syndrome did not differ significantly with respect to age at diagnosis, sex, race, morphology (FAB classification), cell surface markers, initial white blood cell count, pretreatment hemoglobin value, hepatomegaly, lymphadenopathy, presence of mediastinal mass, CNS disease at diagnosis, or prognostic group as defined by age and initial white blood cell count. Patients with ALL-Down syndrome less frequently had splenomegaly, had lower pretreatment platelet counts, and more often had normal or elevated IgG or IgA levels. In addition, they had a significantly lower rate of remission (81% versus 94%), a higher mortality during induction therapy (14% versus 3%), and a poorer overall survival with 5-year life table rates of 50% versus 65% (P less than 0.001). If an initial remission was achieved, there were no significant differences with respect to remission duration, survival, or disease-free survival. Patients with ANLL-Down syndrome were younger at diagnosis than those without Down syndrome. There was no significant difference in the remission rates between these patients. Analysis of findings in patients with ANLL provided results similar to those obtained for patients with ALL with regard to clinical outcome after achievement of an initial remission.

Galactose-induced retinal capillary basement membrane thickening: prevention by Sorbinil

Normotensive and spontaneously hypertensive rats fed a 30% galactose diet until 15-21 months of age developed significant (P less than 0.05) retinal capillary basement membrane thickening, compared with animals fed a standard test diet. Animals on the high galactose diet containing 250 mg/kg of the aldose reductase inhibitor, Sorbinil, did not develop basement membrane thickening. No cytologic abnormalities of pericytes or endothelial cells were noted, and pericyte:endothelial cell nuclear ratios did not differ in the various experimental groups. This model reproduces a characteristic lesion of diabetes mellitus in non-diabetic animals, and should facilitate study of the biochemical mechanisms of basement membrane thickening.

Galactitol accumulation by glucose-6-phosphate deficient fibroblasts: a cellular model for resistance to the complications of diabetes mellitus

When incubated in high galactose media, fibroblasts from individuals with the severe (Mediterranean) variety of glucose-6-phosphate dehydrogenase (G6PD) deficiency accumulate significantly less galactitol than do fibroblasts from matched control subjects. The effect is not observed in fibroblasts from black subjects with the more common, and milder, A- variant of G6PD deficiency. Since aldose reductase and sorbitol dehydrogenase activities in experimental and control fibroblasts are identical, the effect is most likely due to the substantial reduction in NADPH levels in severely G6PD-deficient cells. Sorbitol does not accumulate either in control or in G6PD deficient fibroblasts incubated in high glucose medium, most likely because of the action of sorbitol dehydrogenase, and the presence of a carrier-mediated glucose transport system in the cell membrane which limits the concentration of glucose that can accumulate in these cells.

Aldose reductase activity in retinal and cerebral microvessels and cultured vascular cells

Isolated microvessels (primarily capillaries) from bovine retina and cerebral cortex, as well as cultured bovine retinal capillary pericytes and porcine and canine retinal capillary endothelial cells contain apparent aldose reductase activity. This conclusion is based on the ability of these cultured cells and vessel fragments to reduce DL-glyceraldehyde in preference to D-glucuronate at low (0.1 mM) substrate concentrations, in the presence of NADPH, and in the accumulation of high levels of sorbitol or galactitol when retinal pericytes and endothelial cells are cultured in media enriched in glucose or galactose. The quantitative similarities of these activities in bovine retinal and cerebral microvessels, as well as the quantitatively similar ability of these two sets of microvessels to oxidize 14C-labeled glucose with the label either in the C-1 or the C-6 position, suggests that aldose reductase may not be a major causal factor in diabetic retinopathy. This conclusion is suggested because, while these metabolic activities are similar in bovine retinal and cerebral microvessels, only the retinal microvasculature suffers major anatomic and functional damage in diabetes. This conclusion must be viewed with caution, however, because other metabolic pathways that we have not investigated may be altered by an excess of sugar alcohols, and be present in differing activities in retinal and cerebral microvessels; species differences may exist; and similar experiments have not been conducted using human microvessels.

Peptic ulceration affecting the left ventricle

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Fatal myocardial disease associated with industrial exposure to cobalt

A man of 48 went into cardiac shock under anaesthesia during an operation for a duodenal ulcer. At necropsy he was found to have changes resembling those seen in cobalt cardiomyopathy and his myocardial cobalt level was grossly abnormal. Subsequent investigations established that he had been exposed to cobalt in his work which involved handling the powdered metal. The dangers of cobalt as an industrial hazard are pointed out and it is suggested that cobalt cardiomyopathy should be considered in the differential diagnosis of cardiac disease in those employed in the hard metal industry.

Characteristics of children with acute nonlymphocytic leukemia in long-term continuous remission: a report for Childrens Cancer Study Group

Children and young adults less than 18 years of age with acute nonlymphocytic leukemia who remained in long term bone marrow and extramedullary remission for two years or longer since starting maintenance were compared to the remaining responders for the following characteristics: cell type, sex, age at diagnosis, race, pretreatment, white blood count, length of time from start to induction therapy to achievement of an M1 marrow, marrow rating at day 56 of therapy, marrow rating at the start of maintenance therapy, and specific study. Forty-eight patients of a group of 333 qualified as having long term remission (14.4%). Multivariant analysis indicated that patients between the ages of 3 and 10 years (p = 0.003) as well as the length of time to achieve an M1 marrow from the start of treatment (p = 0.03) were the only characteristics associated with achievement of a long term remission. Maintenance therapy was discontinued in 15 patients from 2.5 to 4.8 years after start of maintenance and all patients remained in bone marrow remission of periods from 0+ to 3.0+ years after stopping treatment. Of the 33 who have remained on a continuous maintenance therapy 12 have had bone marrow relapses. These data confirm the prognostic value of age and length of time to achieve remission during induction in acute nonlymphocytic leukemia and suggest that there may be no significant benefit from maintenance therapy continued beyond 2 years for patients in their initial remission.

Pathology of the intima in coarctation of the aorta: a study using light and scanning electron microscopy

In the adult type of coarctation of the aorta the lumen is constricted by a shelf of fibromuscular tissue that protrudes from the dorsal wall of the aorta at a point near the site of insertion of the ligamentum arteriosum. The intima covering this constricting shelf has been studied using conventional light microscopy and scanning electron microscopy of surgical specimens of coarctation removed at ages varying from 2 to 46 years. Immediately proximal to the stenosis, the intima was found to run in fine longitudinal folds that radiated into the orifice. On the distal side of the shelf the intima was grossly irregular with deep longitudinal and transverse folds that gave it a convoluted appearance resembling the surface of the brain. In adults and older children the intima immediately distal to the orifice was covered with a laminated layer, distinct from the elastica, which often gave positive staining reactions for fibrin. Intimal thickness increased irregularly with age, but large increases of 500 μm or greater were found only in patients over the age of 15 years. These findings are consistent with the view that the constriction has both a fibroelastic component that is congenital and a fibrous component that is acquired and progressive. It is suggested that this progressive element is caused by deposition of fibrin on an abnormal intimal surface in a region of turbulent blood flow. Such a mechanism would explain the occasional recurrence of coarctation of the aorta after surgery. This may be due to failure to remove the abnormal area of endothelium completely and to persistent abnormalities of blood flow at the site of anastomosis.