Showing papers by "Montreal Children's Hospital published in 1980"
TL;DR: The presence of a preauricular pit at birth suggests that the child has at least one chance in 200 of severe hearing loss, and this warrants a careful family history, as well as alertness for any signs of hearing impairment.
Abstract: Nineteen of 421 white children in Montreal schools for the deaf had preauricular pits. The branchio-oto-renal (BOR syndrome was identified in four of the nine families who agreed to family investigation, including audiograms and intravenous pyelograms (IVPs) and may have been present in several others. The penetrance of this autosomal dominant syndrome appears to be high. It is estimated that severe renal dysplasia occurs in about 6% of heterozygotes. The presence of a preauricular pit at birth suggests that the child has at least one chance in 200 of severe hearing loss, and this warrants a careful family history, as well as alertness for any signs of hearing impairment. Offspring of affected individuals are eligible for parental diagnosis of renal dysplasia.
218 citations
TL;DR: New data on methionine consumption due to sarcosine formation permit calculation of a turnover time for S-adenosylmethionine in human liver (no more than 3.5–7 min), as well as upward revision of previous minimal estimates of the rate of methylneogenesis, the number of times that the average homocysteinyl moiety cycles between methionsine and homocysteine during its passage through the body.
Abstract: Estimates of the daily rate of methionine utilization by adult humans, published previously, were under-estimated because available data did not permit quantitative assessment of the rate at which the methyl moiety of methionine is oxidized. 1 The present paper reports efforts to measure the rate of oxidation of methionine methyl by the two pathways that proceed through the intermediate N -methylglycine (sarcosine). Two sarcosinemic, sarcosinuric patients, proven or presumed to have specific genetic defects in the sarcosine-oxidizing system, were studied while maintained on constant diets containing differing amounts of methionine, choline (or choline derivatives), and glycine. The steadystate excretions of sarcosine, creatinine, creatine, and a number of other materials were determined. The results obtained suggest that sarcosine is formed in 2 ways: (1) In an amount equivalent to the dietary intake of choline (or choline derivative)—this pathway would make a net positive contribution to the methionine-methyl pool due to the transfer of a methyl group from betaine to homocysteine; and (2) By processes requiring net consumption of methionine methyl. For the single patient for whom reasonably complete data were attained, it appears that 2 such processes may be occurring. One proceeds at a rate (approximately 2 mmole/24 hr) that changed little as total intake of labile methyl groups ∗ was altered. The second became prominent (and accounted for the bulk of the incremental intake of labile methyl groups) when this intake exceeded the combined amounts required for the synthesis of creatine (10.2 mmole/24 hr), other transmethylation reactions (1.4 mmole/24 hr), polyamine synthesis (0.5 mmole/24 hr), and the “basal” process of sarcosine formation just mentioned (2 mmole/24 hr). It is possible that such “basal” sarcosine formation is due chiefly to endogenous choline synthesis, balanced by degradation, whereas the more responsive process of sarcosine formation may be due chiefly to methylation of glycine. Together with available data, these new data on methionine consumption due to sarcosine formation permit calculation of a turnover time for S-adenosylmethionine in human liver (no more than 3.5–7 min), as well as upward revision of previous minimal estimates 1 of the rate of methylneogenesis, the number of times that the average homocysteinyl moiety cycles between methionine and homocysteine during its passage through the body, and the partitioning of homocysteine between the remethylation and the transsulfuration pathways.
188 citations
TL;DR: The results support the efficacy of home visits, but only if a prenatal visit is included, and suggest that a unique relationship is created between the mother and home visitor and this relationship is sensitive to the timing of the initial encounter.
Abstract: This study is a controlled evaluation of the efficacy of home visits designed to promote better child health and development for infants of working class families. Each of the 115 mother-infant pairs meeting the study criteria was assigned to one of three comparable groups: group A received home visits starting prenatally; group B received visits from six weeks post partum; and group C received no visits. Home observations were completed by an independent evaluator at 6 weeks, 6, 12, and 18 months of age. Significant differences favoring group A over groups B and C were found at each evaluation period. These included: (1) a reduced accident rate; (2) higher scores on assessments of home environment and maternal behavior; and (3) a lower prevalence of mother-infant interaction or feeding problems and of nonparticipant fathers. Aside from a reduction in the accident rate, group B did not benefit from the home visits when compared to control infants. The results support the efficacy of home visits, but only if a prenatal visit is included. These findings suggest that a unique relationship is created between the mother and home visitor and this relationship is sensitive to the timing of the initial encounter.
161 citations
TL;DR: Situations dealing with heterosocial and assertion situations were more difficult for hyperactives than job interview situations and no significant correlations were found between the self-esteem and social skills tests.
Abstract: Eighteen pairs of young adult hyperactives and controls, matched for age, sex, IQ and socioeconomic class and education completed, were assessed on tests of social skills and self-esteem. Hyperactive subjects had significantly more difficulty than matched controls in social skills tests which involved direct oral responses than those involving written responses. This would suggest that the hyperactive young adults cognitively know what the most appropriate response would be from a number of possibilities, but have problems spontaneously producing such a response. Situations dealing with heterosocial and assertion situations were more difficult for hyperactives than job interview situations. Hyperactive young adults also scored significantly worse than matched controls on a number of self-esteem tests, thus supporting the findings of previous psychiatric assessments and the California Psychological Inventory. Finally, no significant correlations were found between the self-esteem and social skills tests. Possible explanations for the findings are discussed.
144 citations
TL;DR: The findings clearly demonstrate that GH can regulate its own secretion via a negative feedback system and suggest that the central nervous system is an important site of action for GH autoregulation.
Abstract: The ability of growth hormone (GH) to regulate its own secretion at the level of the central nervous system was examined in chronically cannulated freely-moving rats. Six-hour GH secretory profiles were obtained from 2 groups of rats administered either normal saline or rat GH via the lateral ventricle of the brain. The typical pulsatile pattern of GH secretion was evident in normal saline-treated control rats with most peak GH values >400 ng/ml. Injection of rat GH (15 yg/10 μl) resulted in a significant suppression in amplitude of GH secretory pulses after an interval of 1 hour and plasma GH levels remained markedly depressed for up to 6 h after injection. Peak GH values did not exceed 76 ng/ml during the latter 3 h of the sampling period. These findings clearly demonstrate that GH can regulate its own secretion via a negative feedback system. Furthermore, the results suggest that the central nervous system is an important site of action for GH autoregulation.
144 citations
TL;DR: It is suggested that a single daily dose of phenobarbital is more effective than counseling parents about antipyretic therapy in preventing recurrent seizures following an initial febrile seizure.
118 citations
TL;DR: The results suggest that the use of anti-Pseudomonas medication in these children may not always be necessary, and observations need to be confirmed by blind-controlled studies in larger numbers of patients with mild as well as severe respiratory involvement.
94 citations
TL;DR: Of the tests used, radionuclide cineangiography appears to be the most sensitive because it can be conveniently applied during the physiological stress of exercise and is likely to be more sensitive than resting measurements of cardiac function.
Abstract: The application of noninvasive techniques to the evaluation of cardiac function in iron overload has identified a high incidence of abnormalities in asymptomatic patients prior to the onset of overt cardiac deterioration. Of the tests we have used, radionuclide cineangiography appears to be the most sensitive because it can be conveniently applied during the physiological stress of exercise. Other tests of cardiac function that include stress are also likely to be more sensitive than resting measurements of cardiac function. Systematic application of these techniques to the study of patients on iron chelation therapy should results in an early determination of the efficacy of such treatment.
62 citations
TL;DR: Plasma levels of 14 amino acids were determined in 44 probands with 3/sec spike-wave epilepsy, 27 of their first-degree relatives, and 22 controls and Tau, Asp, and Tau/Glu were decreased and Glu was increased in both the experimental probands and their first degree relatives.
Abstract: Plasma levels of 14 amino acids were determined in 44 probands with 3/sec spike-wave epilepsy, 27 of their first-degree relatives, and 22 controls. Six ratios of metabolically related amino acids were also calculated. Statistically significant differences were found for 7/20 variables when the experimental and control probands were compared, and for 6/20 variables when the relatives were compared with controls. Tau, Asp, and Tau/Glu were decreased and Glu was increased in both the experimental probands and their first degree relatives. When discriminant analysis was used, age- and sex-matched epileptic probands could be distinguished from the age- and sex-matched control probands with 100% accuracy employing only 3 amino acids (Asp, Glu, Val) and one ratio (Thr/Ser).
61 citations
TL;DR: The demonstration of abundant myofibroblasts within a soft tissue lesion which has been subjected to wide sampling strongly suggests a benign proliferative process as opposed to a malignant neoplasm.
Abstract: A series of 129 soft tissue sarcomas was examined ultrastructurally to determine in which neoplasms and to what extent myofibroblasts could be demonstrated. Twenty cases of fibromatosis and fasciitis served as controls. Myofibroblasts were identified in all 30 cases of malignant fibrous histiocytoma and all 4 cases of well-differentiated sclerosing liposarcoma. Though most numerous in areas of desmoplasia, in no instance did myofibroblasts constitute the dominant cellular constituent of either neoplasm. Myofibroblasts were identified with lesser frequency and in smaller numbers in fibrosarcoma, synovial sarcoma, malignant hemangiopericytoma and neuroblastoma. None were observed in a wide assortment of diverse sarcomas in which desmoplasia was not a feature. In comparison each lesion judged by light microscopy to represent either fibromatosis or fasciitis was composed principally of myofibroblasts. The demonstration of abundant myofibroblasts within a soft tissue lesion which has been subjected to wide sampling strongly suggests a benign proliferative process as opposed to a malignant neoplasm. It is hypothesized that myofibroblasts observed within collagenized regions of soft tissue sarcomas may constitute an expression of host response to neoplasia.
50 citations
TL;DR: During treatment for asthma, a 3-year-old, 15-kg child was given 750 mg of theophylline in error and within three hours she was treated with albumin-collodion activated charcoal (ACAC) hemoperfusion, and the total amount of drug removed was 500.8 mg.
Abstract: During treatment for asthma, a 3-year-old, 15-kg child was given 750 mg of theophylline in error. Within three hours she was treated with albumin-collodion activated charcoal (ACAC) hemoperfusion. Immediately before treatment her serum theophylline level was 74 µg/ml. At the end of three hours of hemoperfusion, her theophylline level had fallen to 14.4 µg/ml and four hours later it was 8.8 µg/ml. The ACAC hemoperfusion system completely removed all the theophylline passing through it without saturation, and the total amount of drug removed was 500.8 mg (more than two thirds of the dose administered). The technique described is an efficient and rapidly effective method for the treatment of potentially lethal theophylline intoxication. For maximum effectiveness, it must be instituted as soon after intoxication as possible.
TL;DR: The energy-restricted diet had no significant effect on nitrogen balance for the entire group when compared with the control dietary intake; however, significant differences in nitrogen balance were noted among individuals at each dietary interval.
Abstract: 1. The effect of an energy-restricted (46 kJ day-1 kg-1), adequate protein diet (1.47 g day-1 kg-1) on the nitrogen metabolism of five obese rapidly growing adolescents (two males and three females) was assessed by means of nitrogen-balance measurements and determination of whole-body nitrogen turnover. 2. The energy-restricted diet had no significant effect on nitrogen balance (P more than 0.1) for the entire group when compared with the control dietary intake; however, significant (P less than 0.01) differences in nitrogen balance were noted among individuals at each dietary interval. 3. Mean values for whole-body nitrogen turnover, protein synthesis and breakdown for the control period were: 45.5 +/- 13.2 mg of nitrogen day-1 kg-1, and 5.72 +/- 1.96 and 5.74 +/- 1.92 g of protein day-1 kg-1 respectively. These values are 82% of those measured in infants. 4. Reducing the mean non-protein energy intake to 20 kJ day-1 kg-1 had no significant effect on whole-body nitrogen turnover, protein syn;thesis or protein breakdown. 5. The results are discussed in relation to the regulation of whole-body nitrogen metabolism, by dietary protein and energy intakes.
TL;DR: A transient "honeymoon period" of adequate oxygenation correlated with good response to tolazoline, and the presence of both was predictive of survival, as well as a significantly higher increase in Pao2 after a test dose of toLazoline than did nonsurvivors.
TL;DR: The cytological light microscopic and ultrastructural study was performed on samples of the CSF obtained during 17 attacks, and the relationship of Mollaret's meningitis to intracranial epidermoid cysts is discussed.
Abstract: Cells, originally called "endothelial" cells, have been described in the cerebrospinal fluid (CSF) of patients developing recurrent aseptic meningitis (Mollaret's meningitis). In an attempt at better establishing their nature, a 6-year-old child was followed for a period of 3 1/2 years. A cytological light microscopic and ultrastructural study was performed on samples of the CSF obtained during 17 attacks. The findings are presented, and the relationship of Mollaret's meningitis to intracranial epidermoid cysts is discussed.
TL;DR: A boy with an astrocytoma in the anterior hypothalamic area and typical features of the diencephalic syndrome of childhood was followed with yearly endocrinological evaluation from 10 months of age until he was 5½‐years‐old and the characteristic clinical features as well as the endocrine findings remain unexplained.
Abstract: A boy with an astrocytoma in the anterior hypothalamic area and typical features of the diencephalic syndrome of childhood was followed with yearly endocrinological evaluation from 10 months of age until he was 5 1/2-years-old. Radiation therapy resulted in temporary clinical improvement. At the time of diagnosis height and bone age were advanced. Basal concentrations of growth hormone (GH) were markedly elevated and could only be partially suppressed by an oral glucose load. There was a paradoxical decline of GH levels following arginine-insulin infusion and an abnormal GH release with TRH administration. Abnormal GH response to the various stimuli persisted for 2 years after radiation therapy. Pituitary secretion of LH, FSH, TSH, prolactin and ACTH remained intact. The characteristic clinical features as well as the endocrinological findings remain unexplained.
TL;DR: The elimination of diuretics and methylxanthines is considerably slower in the neonate than in the adult and dose guidelines must be adjusted to account for this slower drug elimination.
Abstract: The elimination of diuretics and methylxanthines is considerably slower in the neonate than in the adult. Dose guidelines, especially during long term maintenance, must be adjusted to account for this slower drug elimination. Pharmacokinetic studies and the requisite pharmacologic evaluation on diuretics such as hydrochlorothiazide, spironolactone, ethacrynic acid and others should be done. Furosemide undergoes biotransformation in the newborn producing an acid metabolite and a glucuronide conjugate. Methylxanthines are effective in the treatment of neonatal apnea. Plasma elimination of theophylline is exceedingly slow, more so with caffeine. Decreased elimination is partly explained by decreased oxidative biotransformation. Caffeine is excreted in the urine of the newborn mainly unchanged (85%) in contrast to the adult where caffeine is a minor portion of urinary excretion (2%). Theophylline is methylated to caffeine and may possibly exert additive pharmacologic effects.
TL;DR: Modified radiotherapy techniques using wider fields may prevent failure even in those cases diagnosed late and in those with extraocular extension of disease at diagnosis, as well as for intrathecal and systemic chemotherapy in this disease.
Abstract: The results of treatment for 39 consecutive children with retinoblastoma that was diagnosed between 1951 and 1978 were analyzed. Failure to achieve local control within the eye and the development of metastatic disease occurred in seven patients. These patients are considered individually. Delay in diagnosis, older age at presentation, and extraocular extension of disease at diagnosis were associated with treatment failure and were closely interrelated. Modified radiotherapy techniques using wider fields may prevent failure even in those cases diagnosed late and in those with extraocular extension. Indications for intrathecal and systemic chemotherapy in this disease are discussed.
TL;DR: Anaesthetic management of a patient with epidermolysis bullosa dystrophica with oesophageal stricture presenting for colonic interposition is described and the problems associated with this disease are discussed.
Abstract: Epidermolysis bullosa dystrophica is a rare hereditary disorder which presents significant anaesthetic problems. These include malnutrition and anaemia; electrolyte imbalance in severe cases; renal failure and amyloidosis in progressive disease; association with porphyria; a history of steroid therapy. Technical problems associated with the necessity to avoid trauma to the skin and mucous membranes include those related to management of the airway and avoidance of regional techniques. Venepuncture may be difficult and oesophageal stricture increases the risk of regurgitation and aspiration. Anaesthetic management of a patient with epidermolysis bullosa dystrophica with oesophageal stricture presenting for colonic interposition is described and the problems associated with this disease are discussed.
TL;DR: A patient with recurrent severe hypoglycemia resembling Reye's syndrome was found to have large accumulations of omega -- 1 hydroxy and keto acids in serum and urine that persisted following clinical recovery and a deficiency of mitochondrial medium chain acyl CoA dehydrogenase activity is proposed.
Abstract: A patient with recurrent severe hypoglycemia resembling Reye's syndrome was found to have large accumulations of omega -- 1 hydroxy and keto acids in serum and urine that persisted following clinical recovery. A deficiency of mitochondrial medium chain acyl CoA dehydrogenase activity is proposed on the basis of evidence obtained using gas chromatographic mass spectrometric techniques. Analytical data is presented that will allow the recognition of ths variant presenting in other patients.
TL;DR: Various metabolic studies were performed in a patient with the idiopathic Fanconi syndrome in whom constant ketonuria suggested that organic acidemia might contribute to the metabolic acidosis, suggesting an altered intracellular redox state with an abnormally high NADH:NAD+ ratio.
Abstract: Various metabolic studies were performed in a patient with the idiopathic Fanconi syndrome in whom constant ketonuria suggested that organic acidemia might contribute to the metabolic acidosis. Glucose intolerance with a diminished insulin release was found after PO or IV glucose loads and after glucagon administratio. An insulinopenic "diabetes-like" state has not previously been described in such patients. The patient had impaired galactose-glucose interconversion, elevated blood lactate levels, reduced pyruvate levels, and an increased lactate:pyruvate ratio. Hepatomegaly and hypoglycemia were not present, and liver and muscle biopsies revealed no enzymatic evidence of glycogenosis. The erythrocyte UDP galactose transferase activity was normal. The patient failed to convert fructose to glucose and had a rise in blood lactate after ethanol administration. Further studies revealed no production of glucose after alanine or glycerol administraion, each test being associated with elevated blood lactate levels and, after alanine, an increased lactate:pyruvate ratio. The lactate:pyruvate ratio was elevated after glucagon administration with increased lactate and reduced pyruvate concentrations.
TL;DR: Diabetic children in the multiplex and simplex families did not differ in the month of onset of symptoms nor in the age at diagnosis although three multiplex pedigrees in which diabetes developed in all affected children before the age of 6 years were identified.
Abstract: Families (n = 14) with more than 1 sibling with insulin dependent diabetes were matched with families of similar size and age distribution containing only 1 affected child. The distribution of HLA haplotypes, age of onset of disease, and seasonal onset of disease were compared in the two groups. The data are not consistent with the hypothesis of a single autosomal recessive gene linked to the HLA region. The data do not permit a choice between other current hypotheses although they are compatible with the theory of 2 genes linked to the HLA region, acting additively, and requiring interaction either with environmental factors or other disease susceptibility genes. Diabetic children in the multiplex and simplex families did not differ in the month of onset of symptoms nor in the age at diagnosis although three multiplex pedigrees in which diabetes developed in all affected children before the age of 6 years were identified.
TL;DR: Two children who developed osteogenic sarcoma following treatment with megavoltage radiation and combination chemotherapy for primary bone tumors are seen, and the implications in regard to aggressive multimodality treatment for pediatric malignancies are discussed.
Abstract: While osteogenic sarcoma has been well-recognized as a late complication of exposure to high doses of ionizing radiation in the orthovoltage energy range, it has been less frequently reported in patients treated with megavoltage radiation. This potential complication should, however, not be dismissed as an occurrence to be seen only after high-dose orthovoltage radiation. We have recently seen two children who developed osteogenic sarcoma following treatment with megavoltage radiation and combination chemotherapy for primary bone tumors. The implications in regard to aggressive multimodality treatment for pediatric malignancies are discussed.
TL;DR: A case report of a patient with Von Gierke's (glycogen storage disease Cori type (1)1 disease) who required femoral osteotomy is presented and current techniques of management are discussed.
Abstract: A case report of a patient with Von Gierke's (glycogen storage disease Cori type (1)1 disease who required femoral osteotomy is presented. Current techniques of management of this condition which are likely to improve the outcome of general anaesthesia and surgery are discussed.
TL;DR: It is demonstrated that platelet aggregation is reduced in the early phase of the HUS, when the platelet count was below 100,000/mm3 and after the Platelet count had normalized.
Abstract: Platelet aggregation was studied in three patients during the course of the hemolytic-uremic syndrome (HUS) when the platelet count was below 100,000/mm3 and after the platelet count had normalized Platelet aggregation was examined in response to epinephrine, adenosine diphosphate (ADP) and collagen Aggregation did not occur in response to epinephrine when the patients were thrombocytopenic but normal tracings were obtained when the platelet counts had returned to normal In contrast, platelet-rich plasma from normal subjects diluted with platelet-poor plasma from patients to comparable platelet counts, showed normal aggregation responses This study demonstrates that platelet aggregation is reduced in the early phase of the HUS
TL;DR: The induction of meningitis in a predictable fashion without disrupting the blood-brain barrier and the ability to study the cerebrospinal fluid without killing the animal make this a useful model of human neonatalMeningitis caused by E. coli K1.
Abstract: A total of 88 neonatal guinea pigs was inoculated intranasally with a clinical isolate of Escherichia coli K1 that had been passaged once in the peritoneum of an adult guinea pig; 74 animals became bacteremic, of which 54 had meningitis, 12 hr after inoculation. Bacteremia and/or meningitis occurred consistently in repeated experiments. It was possible to obtain serial specimens of cerebrospinal fluid by cisternal puncture without killing the animals. The induction of meningitis in a predictable fashion without disrupting the blood-brain barrier and the ability to study the cerebrospinal fluid without killing the animal make this a useful model of human neonatal meningitis caused by E. coli K1.
TL;DR: Specificity of the serologic results of SPA-treated infant sera correlated with IgM-specific identification of the causative agent, and persistence of greater than or equal to 25% of the original antibody titer following SPA adsorption distinguished the sera of infants with congenital infection from those of healthy infants.
TL;DR: A child with common prostatic urethra with two normal, double urethras parallel to one another with a bifid glans penis is presented, emphasizing how abnormal embryology can contribute to the authors' knowledge of normal development.
TL;DR: In this paper, an 11.5-year-old boy presented with a history of hypernasal for 1.5 years, but there was no nasal escape and the child had been on speech therapy and the recommendation was that the therapy be stopped.
TL;DR: The importance of the concept of traumatic neurosis with its emphasis on the inner world of the child, must leave the diagnostician ever aware of the inner worlds of the parents and to the dynamics of family life.
Abstract: On revient ici au cas precedemment expose d'un jeune garcon victime d'un choc grave. Le premier rapport decrivait les concepts du choc emotionnel et de la nevrose traumatique et interpretait le cas...
TL;DR: None of the surfactants tested affected the rate of hexosaminidase A-catalysed hydrolysis of 4-methylumbelliferyl N-acetyl-beta-d-glucopyranoside and inhibitory surfactant are competitive with the activator protein.
Abstract: The effects of surfactants on the human liver hexosaminidase A-catalysed hydrolysis of G(m2) ganglioside were assessed. Some non-ionic surfactants, including Triton X-100 and Cutscum, and some anionic surfactants, including sodium taurocholate, sodium dodecyl sulphate, phosphatidylinositol and N-dodecylsarcosinate, were able to replace the hexosaminidase A-activator protein [Hechtman (1977) Can. J. Biochem.55, 315-324; Hechtman & Leblanc (1977) Biochem. J.167, 693-701) and also stimulated the enzymic hydrolysis of substrate in the presence of saturating concentrations of activator. Other non-ionic surfactants, such as Tween 80, Brij 35 and Nonidet P40, and anionic surfactants, such as phosphatidylethanolamine, did not enhance enzymic hydrolysis of G(m2) ganglioside and inhibited hydrolysis in the presence of activator. The concentration of surfactants at which micelles form was determined by measurements of the minimum surface-tension values of reaction mixtures containing a series of concentrations of surfactant. In the case of Triton X-100, Cutscum, sodium taurocholate, N-dodecylsarcosinate and other surfactants the concentration range at which stimulation of enzymic activity occurs correlates well with the critical micellar concentration. None of the surfactants tested affected the rate of hexosaminidase A-catalysed hydrolysis of 4-methylumbelliferyl N-acetyl-beta-d-glucopyranoside. Both activator and surfactants that stimulate hydrolysis of G(m2) ganglioside decrease the K(m) for G(m2) ganglioside. Inhibitory surfactants are competitive with the activator protein. Evidence for a direct interaction between surfactants and G(m2) ganglioside was obtained by comparing gel-filtration profiles of (3)H-labelled G(M2) ganglioside in the presence and absence of surfactants. The results are discussed in terms of a model wherein a mixed micelle of surfactant or activator and G(M2) ganglioside is the preferred substrate for enzymic hydrolysis.