Joseph Dancis

Transfer across the perfused human placenta of antipyrine, sodium and leucine.

Abstract The transfer of antipyrine, sodium, and l -leucine across an isolated cotyledon of human placenta was studied with an in vitro perfusion system. Antipyrine transfer was flow limited. If an efficiency of extraction approximately that of a pool type of flow pattern is assumed, 50 to 80 per cent of the maternal perfusate was presented to the placental membrane for exchange. Sodium exchange rate was about 25 per cent that of antipyrine clearance, indicating a diffusion limitation very similar to that for monkey placenta as measured in situ. The calculated hourly exchange of sodium per gram of placenta varied between 4.2 and 11.4 mg. which compares favorably with in vivo measurements in the human term gestation. The l -leucine transfer rate approximated that for sodium.

Maple Syrup Urine Disease

Serum amino-acid chromatogram. Note the intense leucine/isoleucine and valine spots. bronchopneumonia at 3 weeks, was drowsy from birth and fed poorly. Examination showed our patient to be unresponsive, with increased tone and occasional opisthotonic spasms. A strong odour of maple syrup was present. Investigations.-Urinary chromatograms showed marked increase in valine (from which the odour was detected), leucine, and isoleucine, with moderate increases in other amino-acids. The a-keto acids of the branched amino-acids were also present in large amounts. Indolyl-lactic acid was present in excess but not indolyl-acetic acid. Asparagine and ethanolamine were also detected. The serum and cerebrospinal fluid showed greatly increased amounts of valine,leucine, and isoleucine; other amino-acids were normal or low in quantity (see Fig.). COMMENT.-While clinically this case is one of maple syrup urine disease the biochemical findings suggest the presence of a renal tubular defect and hepato-cellular damage. Previously reported cases have shown an increase in indolyl-acetic acid; this was not present in the above case. Detailed biochemical findings will be published later, with the results of a dietary trial which is proceeding.

A grid for recording the weight of premature infants

Summary A grid is presented showing expected weight curves for premature infants of varying birth weights. Its usefulness and limitations are discussed.

Quantitative studies of dorsal root ganglia and neuropathologic observations on spinal cords in familial dysautonomia

Intrauterine development and postnatal maintenance of dorsal root ganglion neurons are abnormal in familial dysautonomia, an autosomal recessive disorder associated with autonomic, motor and sensory deficits. Normally, dorsal root ganglion weight increases with age. This does not occur in the cervical plexus ganglia of dysautonomic patients. Neurons in dorsal root ganglia are found to be markedly diminished in the youngest patients and slow degeneration causes further depletion with age. Quantitative studies on C8 dorsal root ganglia show the normal neuron content to be between 42,500 and 53,600. In 3 patients with familial dysautonomia the range was 4,090-8,590 with the smallest number being in the oldest patient. Lateral root entry zones and Lissauers tracts are severely depleted of axons. In older patients loss of dorsal column myelinated axons becomes evident and is first seen in lumbar fasciculus gracilis, cervical fasciculus cuneatus and interfascicular fasciculus. Temperature sensation is markedly impaired from infancy in familial dysautonomia. Loss of pain sensation is prominent and worsens with age. Vibration sense diminishes in adolescence and coordination of limb movements becomes poor in older patients. Neuron depletion in dorsal root ganglia and the progressive pattern of cord changes correlate well with these clinical observations.

Conversion of lysine to saccharopine by human tissues

Abstract The ability of human tissues to convert lysine and α-ketoglutarate to saccharopine [ e-N-( l -glutaryl -2)- l -lysine ] has been investigated vitro. Liver is the most effective organ, though some activity could be demonstrated in several other tissues. The responsible enzyme lysine-ketoglutarate reductase (lysine:α-ketoglutarate: TPNH oxidoreductase ( e-N-[ glutaryl -2]- l -lysine forming )) has been partially purified from human liver and optimal conditions for its assay determined. There is a specific requirement for TPNH that cannot be satisfied by DPNH. A pH optimum near neutrality and inhibition by ammonium sulfate were observed. The enzyme is stable at −25°, both in tissues obtained at post-mortem and in its purified form. The assay for lysine-ketoglutarate reductase is sufficiently sensitive to be used on the limited amount of tissue obtainable by needle biopsy of the liver.

CURRENT CONCEPTS OF DYSAUTONOMIA: NEUROPATHOLOGICAL DEFECTS*

The complexity of the clinical picture in familial dysautonomia (FD)1 makes it difficult to identify any single underlying congenital defect. Corneal anaesthesia, poor taste discrimination, deficient vestibular reflexes, and insensitivity to pain and temperature indicate sensory abnormalities. The absence of a flare in response to intradennal injection of histamine points to absence of function in parts of the peripheral components of sensory axons.2 Some of the anticipated responses to sympathomimetic and parasympathomimetic agents are exaggerated, suggesting denervation supersensitivity or imbalance of autonomic system functions. Thus, the observed exaggerated hypertensive response to infusion of low doses of norepinephrine might suggest denervation hypersensitivity,3 and the absence of reflex bradycardia raises the question of parasympathetic insufficiency. The latter possibility is supported by the meiotic reaction of the pupil to instillation into the conjunctival sac of dilute methacholine’ which would be subthreshold in a normal subject, whereas dilute sympathomimetic agents do not produce dilation. The possibility of cholinergic insufficiency appears strengthened by the observation that intravenous methacholine produces overflow tears, restoration of the knee jerk, and return of the histamine flare, thus reversing temporarily three of the cardinal abnormalities of familial dysautonomia.5 Some of these responses could represent pharmacological effects rather than replacement therapy. The clinical course of the disease includes characteristic crises in which the children become irritable, wirh occasional screaming attacks, lose their power of concentration, and show marked hypersensitivity of their hair, feet, and genitalia which causes them to object vehemently to being touched in these areas. Occasionally, the cranial hair is said to !‘stand on end.” The crises are also marked by vomiting, hypertension, fever, symmetrical blotching of the skin, and puffy, red, cold hands. The hypertension and symmetrical blotching can be reproduced by infusion of norepinephrine.3 Eating often leads to sweating, primarily on the head and occasionally on the back. The soles of the feet and palms of the hand do not sweat. Mature males are capable of penile erection, but ejaculation apparently does not occur. Children with dysautoxiomia characteristically fail to form overflow tears, but there is sufficient function of the lacrimal glands to keep the eyes moist. Orthostatic hypotension and wide fluctuations in body temperature unrelated to environmental temperature also suggest autonomic dysfunction. Excretion of norepinephrine and methoxy-hydroxy-mandelic acid, which is largely derived from the breakdown of norepinephrine, are reduced in FD, but the required catabolic enzymes remain intact.6 Norepinephrine produced by hydroxylation of dopamine, is the immediate precursor of epinephrine. The presence in the urine of normal amounts of Iiomovanillic acid, which is derived from d o p

Intermittent Branched-Chain Ketonuria: Variant of Maple-Syrup-Urine Disease

MAPLE-syrup-urine disease (branched-chain ketonuria) is a genetic disorder with a well defined biochemical defect.1 Symptoms of anorexia, vomiting, hypertonicity and occasionally convulsions appear...

The Effect of Hypoxia on Human Trophoblast in Culture: Morphology, Glucose Transport and Metabolism

The response to hypoxia of trophoblast isolated from term placenta and maintained in culture was studied. Trophoblast exposed to normoxic (PO2 120-130 mmHg) or hypoxic (PO2 12-14 mmHg) conditions were examined by electron microscopy. After 48 h, the cytoplasm of the hypoxic cells was more electron-dense with increased numbers of mitochondria, lysosomes and vacuoles. Compared to normoxic cells, the surface microvilli of the hypoxic cells were sparse, short and unevenly distributed. [3H]thymidine incorporation by both hypoxic and normoxic trophoblast fell rapidly and equivalently after 2 days in culture. The percentage of cells with the proliferation-associated nuclear antigen, Ki 67, also decreased, but remained higher in hypoxic cells suggesting that hypoxia retarded completion of the cell cycle (normoxia, 10.80 +/- 2.51 s.e.; hypoxia, 19.87 +/- 2.73, P < 0.01). Glucose consumption was elevated in hypoxia (3.73 +/- 1.07 s.e. mumol/10(6) cells/24 h) as compared to normoxia (1.46 +/- 0.83, P = 0.01). Although lactate production was consistently higher in hypoxia, the difference was not statistically significant (hypoxia 5.38 +/- 1.54 mumol/10(6) cells/24 h versus normoxia, 1.52 +/- 0.29, P = 0.07). After 48 h, uptake of [3H]2-deoxglucose ([3H]2DG) by hypoxic cells was reduced to 12 per cent +/- 4.3 s.e. of that in normoxic cells; return to normoxia resulted in recovery within 10 min. Lineweaver-Burk plots of [3H]2DG uptake indicated high affinity (KM 2.2 +/- 0.4 x 10(-4) M) and low affinity transporters (KM 4.5 +/- 1.6 x 10(-3) M). Northern blot analysis identified mRNA for GLUT1 and GLUT3. In hypoxia, steady-state GLUT1 and GLUT3 mRNA were approximately three- and 10-fold higher than in normoxia respectively. Inhibitors of oxidative metabolism of glucose increased the uptake of [3H]2DG within 2 h, whereas hypoxia reduced uptake. Hence, trophoblast in culture survives in extreme hypoxia, but manifests striking changes in morphology and in glucose metabolism and transport. Completion of cell cycle appears to be retarded.

The transfer and metabolism of corticosteroids in the perfused human placenta.

The transfer and metabolism of cortisol, prednisolone, betamethasone, and dexamethasone were investigated in vitro in the perfused human placenta. Maternal and fetal circuits were established but the steroid was added to the former only. The clearance expressed as a fraction of the antipyrine transfer rate varied from 0.27 to 0.50, but there were no significant differences among the four steroids. All the steroids were metabolized extensively to their respective 11-ketosteroids and again there were no material differences among the steroids. The metabolic conversions of dexamethasone and betamethasone were far greater in the perfused placenta than in minced placenta. From the standpoint of placental transfer and metabolism, as observed in the perfusion studies, none of the four corticosteroids offers a decisive advantage in the antepartum maturation of the fetal pulmonary surfactant system.

Transport of amino acids by placenta.

Abstract Placental transport has been studied in vivo in the guinea pig and in vitro with guinea pig and human placenta. Following the infusion of the nonmetabolized amino acid, AIB- 14 C, into pregnant guinea pigs for 2 to 4 hours, the fetal plasma concentration of the amino acid exceeded that in the maternal plasma. The concentration of the amino acid in maternal placenta (decidua) exceeded that in the maternal plasma. The concentration in the fetal placenta was higher than in both the maternal and fetal plasma, suggesting that transport may involve at least two steps, concentrative uptake into the placenta and release into fetal plasma. Perfusion of guinea pig placenta in situ, following removal of the fetus, demonstrated the primary role of the placenta in establishing a concentration gradient toward the fetus. It was also demonstrated that the amino acid was transferred across the placenta in both directions, apparently more rapidly toward the fetus than in the reverse direction. In vitro experiments with guinea pig and human placenta revealed concentrative uptake of the amino acid. This was decreased by metabolic poisons. The isolated villus of human placenta concentrated the amino acid more effectively than did placental slices. Insulin increased uptake into human placenta but not into guinea pig placenta. Growth hormone, lactogenic hormone, estradiol, estrone sulfate, and oxytocin produced no measurable response.