Hypophosphatasia: a cytochemical study of phosphatase activities

Skeletal abnormalities with defective formation of mature calcified bone are the most prominent clinical features of hypophosphatasia. Low concentrations of serum and tissue alkaline phosphatase and elevated plasma and urinary levels of phosphorylethanolamine (PEA) are also present. Although PEA is hydrolyzed by serum alkaline phosphatase, the relationship between PEA and the deficiency is unclear. PEA has not previously been tested as a cytochemical substrate for the in situ demonstration of human alkaline phosphatase activity. We have studied alkaline phosphatase activity in hypophosphatasia in tissue sections, utilizing PEA and adenosinetriphosphate (ATP) as well as the usual beta-glycerophosphate and naphthol phosphate substrates. Neutral and acid phosphatase activities were also examined. Our results demonstrate that PEA is a substrate for the localization of alkaline phosphatase in normal human tissue, but is not hydrolyzed in hypophosphatasia in the liver, brain or costochondral junction under alkaline conditions. In the kidney in hypophosphatasia only the straight segments of proximal tubules that rim the medullary rays are reactive with PEA. Similar results in hypophosphatasia were obtained at an alkaline pH with ATP, beta-glycerophosphate, and naphthol phosphate. However, the defect in hypophosphatasia is not a generalized deficiency of membrane-associated phosphatases because membranes that were deficient in alkaline phosphatase activity demonstrated normal reactivity with ATP at neutral pH. In addition, thiamine pyrophosphate was also split by Golgi membranes within the cytoplasm. Acid hydrolysis of beta-glycerophosphate by lysosomes was normal.

Histochemical characteristics of the striated inclusions of adrenoleukodystrophy

The straited accumulations in adrenal cortical cells and brain macrophages that are characteristic of adrenoleukodystrophy have been studied histochemically in cryostat sections to seek leads for the biochemical identification of the striated material. It stained pale pink with oil red O and did not stain with the Schultz cholesterol procedure or periodic acid-Schiff technique. By utilizing the birefringence of the accumulations as a marker, it was determined that, unlike natural cholesterol and cholesterol esters, the striated material was resistant to acetone and ethanol extraction. It was readily soluble, however, in nonpolar solvents such as n-hexane and chloroform. These findings indicated that the material was most probably a lipid, and they suggested that sequential extraction of adrenoleukodystrophy adrenal and brain with acetone and then n-hexane could be used to isolate this material in relatively pure form. Based on this lead, biochemical studies have just revealed a fatty acid abnormality in adrenoleukodystrophy which appears to be unique to this genetic disease.

GM2-gangliosidosis, AB variant: clinico-pathological study of a case

Clinical and neuropathological studies of a case of AB variant GM2-gangliosidosis have been presented. The patient was a 14 months old black female infant who had "black cherry spot" in the retinas. The total activities of beta-galactosidase and N-acetyl-beta-hexosaminidase, as well as the proportion of hexosaminidase A and B components in her serum and leukocytes were normal when the assays were carried out with artificial fluorogenic substrate. Diagnosis of GM2-gangliosidosis AB variant was established by an abnormal increase of GM2-ganglioside in the biopsied brain tissue, similar to classical Tay-Sachs disease. Her clinical manifestation appeared to be similar but somewhat milder than those of classical Tay-Sachs disease. Light microscopic features of the cerebral biopsy were also closely similar to Tay-Sachs disease and Sandhoff disease but gliosis and neuronal loss were less pronounced. Electron microscopic study revealed numerous membranous cytoplasmic bodies (MCB) and zebra bodies in neurons. In addition, varieties of large intracytoplasmic inclusions in astrocytes, a feature distinctly different from classical Tay-Sachs disease, were observed. Numerous cytoplasmic inclusions were also present in oligodendroglia, pericytes and microglial cells.

Vesicular disruption of myelin in autoimmune demyelination

A pattern of autoimmune demyelination in EAE and EAN has been described which was encountered consistently and was sometimes more common than the better known phenomenon of active stripping of myelin by macrophages. This pattern involved the rapid dissolution of myelin into a vesicular network which was later degraded by macrophages. It occurred early in the disease, was not accentuated perivascularly, and was usually associated with the presence of macrophases. The underlying mechanisms are not known but several alternatives have been discussed, viz., activity of locally released antibody, cytotoxic factors, or hydrolytic enzymes.

Solitary neonatal hepatic abscess

A solitary hepatic abscess was found at postmortem examination in a neonate who died at 25 days of age. Elevation of the right diaphragm was noted radiologically from the first day of life, suggesting congenital presence of the abscess. Recognition of the previously unsuspected association between hepatic abscess and congenital diaphragmatic elevation might have led to surgical intervention and have increased the infant's chance of survival.

Peroxisomal and mitochondrial defects in the cerebro-hepato-renal syndrome

The cerebro-hepato-renal syndrome is a rare familial malady with cerebral, renal, and skeletal abnormalities, severe hypotonia, cirrhosis, iron and lipid storage, and death within 6 months. Correlated electron microscopic, histochemical, and biochemical studies demonstrate defects in two oxidative organelles. Peroxisomes cannot be found in hepatocytes and renal proximal tubules. In hepatocytes and cortical astrocytes, mitochondria are distorted in their appearance and glycogen stores are increased. Oxygen consumnption of brain and liver mitochondrial preparations with succinate and with substrates reducing nicotinamide adenine dinucleotide is markedly diminished, but the consumption is normal with ascorbate and tetramethylphenylenediamine, which suggests a defect in electron transport prior to the cytochromes. Histochemical studies of mitochondrial oxidation point to a defect between the succinate dehydrogenase flavoprotein and coenzyme Q, possibly in the region of nonheme iron protein.

Specific binding of peroxidase-labeled myelin basic protein in allergic encephalomyelitis

A conjugate of horseradish peroxidase and the encephalitogenic basic protein from myelin has been used to study the antigen reactivity of tissue in the autoimmune disease, experimental allergic encephalomyelitis. Control conjugates were also prepared of peroxidase and bovine serum albumin and of peroxidase and lysozyme, another basic protein. The basic protein from myelin conjugate was specifically bound by lymph node cells from rabbits immunized against the basic protein. Some of these cells appeared to be plasma cells. The conjugate was also specifically bound by occasional cells in the spinal-cord infiltrates of animals with early signs of allergic encephalomyelitis. These cells resembled large lymphocytes and plasma cells. There was no difference between the binding of basic protein of bovine and rabbit origin. The findings suggest the possibility that a local release of antibody within the target organ may play a role in the pathogenesis of allergic encephalomyelitis.

The use of phenazine methosulfate for improving the histochemical localization of ketose reductase (L-iditol:NAD oxidoreductase, or sorbitol dehydrogenase)

An improved histochemical localization of the activity of ketose reductase, a nicotinamide adenine dinucleotide-dependent enzyme, was achieved by using an incubating medium containing phenazine methosulfate. Fixed sections of mouse male accessory reproductive glands, liver and kidney reacted faster in the presence of phenazine methosulfate, yet without the false localizations found with media lacking this compound. At the cytologic level, phenazine methosulfate caused a fine deposition of formazan in the cytoplasm of all reactive tissues, whereas without it granules presumed to represent mitochondria were stained. Phenazine methosulfate is believed to produce these effects by serving as an intermediate electron acceptor between reduced coenzyme and tetrazolium. Thus detectable diffusion of reduced coenzyme did not occur because phenazine methosulfate improved trapping. The concentrations of both phenazine methosulfate and coenzyme were critical in obtaining accurate cytologic localization. The use of cyanide with phenazine methosulfate, although necessary with unfixed tissues, was not essential with fixed tissues.

Histochemical demonstration of the soluble enzyme, ketose reductase (sorbitol dehydrogenase), by utilizing a new fixing solution

Localization of the activity of the soluble enzyme, ketose reductase, was made possible by using a high-tonicity fixative containing formalin, ethanol, and tris (hydroxymethyl)aminomethane and by maintaining high tonicity in the incubating medium. Incubations could be performed at pH 8.8, an optimal pH for the conversion of sorbitol to fructose.

False localization, probably resulting from diffusion of the first reactions product, reduced nicotinamide adenine dinucleotide, was minimized by slowing the reaction rate and using less tissue in the incubating medium. When this medium was tested with phenazine methosulfate, neither reduced nicotinamide adenine dinucleotide nor soluble dehydrogenase activity was detected.

Ketose reductase activity was demonstrable throughout the epithelia of the seminal vesicle and the coagulating gland of the mouse. The activity was greater in the coagulating gland. It also was present in spermatozoa, central hepatic parenchymal cells, and renal proximal tubule. It was not present in the vas deferens epithelium nor ganglion cells. Reactivity in smooth muscle was believed to be artifact.

II. Stereoscopic Radiography

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