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Biomedical subjects

M A Clarke

Publications and source records attributed to M A Clarke.

At least 19 recordsLinked to original sources
PubMed1998

Sucrose loss and color formation in sugar manufacture.

The chemical reactions contributing to sucrose loss and color formation in evaporators in sugar manufacture (i.e., hydrolysis of sucrose and degradation of monosaccharides at acid pH) are reviewed. A case study of a sugar factory's evaporator system demonstrates that the measurement of small but real losses of sucrose across the process is not possible by conventional sugar factory analyses. Alternative, more accurate techniques (e.g., capillary gas chromatography or high performance ion chromatography [HPIC] with pulsed amperometric detection [PAD]) are considered. In the case study, glucose:sucrose ratios are determined by HPIC, and sucrose loss across the evaporator is estimated to be 1.39% of total sucrose. Loss measurements are thought to be underestimates; reasons for underestimation and the sources of errors are discussed. An approach to a more definitive loss measurement is proposed.

Color↗
PubMed1997

The clinical phenotype of succinic semialdehyde dehydrogenase deficiency (4-hydroxybutyric aciduria): case reports of 23 new patients.

OBJECTIVES: To further define the clinical spectrum of the disease for pediatric and metabolic specialists, and to suggest that the general pediatrician and pediatric neurologist consider succinic semialdehyde dehydrogenase (SSADH) deficiency in the differential diagnosis of patients with (idiopathic) mental retardation and emphasize the need for accurate, quantitative organic acid analysis in such patients. PATIENTS: The clinical features of 23 patients (20 families) with SSADH deficiency (4-hydroxybutyric acid-uria) are presented. The age at diagnosis ranged from 3 months to 25 years in the 11 male and 12 female patients; consanguinity was noted in 39% of families. OUTCOME MEASUREMENTS: The following abnormalities were observed (frequency in 23 patients): motor delay, including fine-motor skills, 78%; language delay, 78%; hypotonia, 74%; mental delay, 74%; seizures, 48%; decreased or absent reflexes, 39%; ataxia, 30%; behavioral problems, 30%; hyperkinesis, 30%; neonatal problems, 26%; and electroencephalographic abnormalities, 26%. Associated findings included psychoses, cranial magnetic resonance or computed tomographic abnormalities, and ocular problems in 22% or less of patients. Therapy with vigabatrin proved beneficial to varying degrees in 35% of the patients. Normal early development was noted in 30% of patients. CONCLUSIONS: Our data imply that two groups of patients with SSADH deficiency exist, differentiated by the course of early development. Our recommendation would be that accurate, quantitative organic acid analysis in an appropriate specialist laboratory be requested for any patients presenting with two or more features of mental, motor, or language delay and hypotonia of unknown cause. Such analyses are the only definitive way to diagnose SSADH deficiency; the diagnosis can be confirmed by determination of enzyme activity in white cells from whole blood. We think that increased use of organic acid determination will lead to increased diagnosis of SSADH deficiency and a more accurate representation of disease frequency. As additional patients are identified, we should have a better understanding of both the metabolic and clinical profiles of SSADH deficiency.

Adolescent↗
PubMed1997

Adenomyoepithelioma of the breast.

Adenomyoepithelioma is a rare disorder characterised by simultaneous proliferation of ductal epithelium and myoepithelial cells. It is more common in salivary glands or skin, and only rarely found in breast tissue. Adenomyoepithelioma of the breast was first described in 1970 by Hamperl. Since then, approximately 55 cases have been described in the literature; the largest review, by Tavassoli in 1991, reported 27 of these cases. Because of the small number of cases reported, the natural history of adenomyoepithelioma of the breast remains uncertain. We report a further case which was treated by local excision, and follow-up for two years has revealed no evidence of local recurrence or metastatic spread.

Adult↗
PubMed1996

Familial bilateral periventricular nodular heterotopia mimics tuberous sclerosis.

A mother and daughter with an initial diagnosis of tuberous sclerosis are described. The daughter presented with partial seizures at the age of 8 months. Computed tomography showed uncalcified periventricular nodules which on magnetic resonance imaging were ovoid, almost contiguous, of grey matter density, and did not enhance with gadolinium. Brain imaging of her asymptomatic mother was similar. Absence of severe mental retardation, extracranial hamartomas, and depigmented patches distinguishes familial bilateral periventricular nodular heterotopia (FNH) from tuberous sclerosis. FNH is probably inherited as an X linked dominant with lethality in males.

Adult↗
PubMed1993

Dysembryoplastic neuroepithelial tumour as a potentially treatable cause of intractable epilepsy in children.

Dysembryoplastic neuroepithelial tumour (DNT) represents a morphologically unique and surgically treatable benign lesion typically associated with complex partial seizures (CPS). Although the radiological features are not pathognomonic the histology is quite distinct. They may account for a significant minority of children with intractable CPS. We present four histologically proven cases to demonstrate and discuss the range of radiological features. Recent recognition that CPS may be caused by a number of conditions including DNT emphasizes that all children with partial seizures should have radiological investigations early in their course.

Brain↗
PubMed1993

Cranial hemihypertrophy with ipsilateral naevoid streaks, intellectual handicap and epilepsy: a report of two cases.

Two cases are described which presented with diffuse swelling of one cheek and hypertrophy of the underlying maxilla and mandible. Both children developed verrucous pigmented streaks over the area of swelling, and had epilepsy and severe mental subnormality. One of the children had a contralateral hemiplegia and his condition had a progressive course. The other child had no focal neurological signs and his disease seemed to be non-progressive. Although the facial appearance of both children suggested the diagnosis of encephalocrainiocutaneous lipomatosis syndrome, it was not possible to demonstrate the presence of any lipomata in either case. The literature relating to encephalocraniocutaneous lipomatosis is reviewed, as well as that relating to the syndromes of naevus unius lateris, the Proteus syndrome and the syndrome of cranial hemihypertrophy, and the clinical features of our two cases are compared with the features of these four syndromes.

Brain↗
PubMed1993

Occurrence of Duchenne dystrophy in Klinefelter's syndrome.

A boy with Duchenne muscular dystrophy and facial dysmorphism in conjunction with Klinefelter's genotype 47XXY is presented; this is an unusual situation with two genetic errors evolving over two generations. Karyotyping should be considered in boys with Duchenne muscular dystrophy who have unusual features.

Child, Preschool↗
PubMed1992

Fatal liver failure following generalized tonic-clonic seizures.

We present three cases of fatal hepatic necrosis in patients with epilepsy taking anticonvulsants, in which the terminal illness presented as an unusually severe generalized tonic-clonic seizure with failure to regain consciousness. In two cases acute renal failure also occurred. It is not certain to what extent drug therapy, physiological and metabolic changes consequent on prolonged seizures, hitherto undiscovered infective agents, or a combination of any of these may play in such a process. We suggest, however, that the case against the drugs alone has yet to be proved.

Acidosis↗
PubMed1987

Differential effects of manoalide on secreted and intracellular phospholipases.

Manoalide, a novel nonsteroidal sesterterpenoid, is a potent inhibitor of phospholipase A2 isolated from bee and cobra venoms. This report compares the inhibition by manoalide of phospholipase A2 in crude cytosol fractions from four mammalian tissues with that of four purified extracellular phospholipase A2's. Phospholipase A2 isolated from bee venom (Apis mellifera) was the most sensitive to inactivation by manoalide (IC50 approximately equal to 0.12 microM). Extracellular phospholipase A2 from rattlesnake and cobra venom was intermediate in sensitivity to manoalide (IC50 values of 0.7 and 1.9 microM respectively). Porcine pancreatic phospholipase A2 was relatively resistant to inactivation by manoalide (IC50 approximately equal to 30 microM). The phospholipase A2 assayed in crude cytosol fractions from four mammalian tissues exhibited IC50 values of 30 microM or greater. Cytosolic proteins as well as bovine serum albumin and poly-L-lysine (Mr = 57,000) protected purified bee venom phospholipase A2 from inactivation by manoalide. In contrast, amino acids such as lysine and alanine failed to protect the purified enzyme from inactivation. Proteins and certain amino acids, such as lysine, formed a chromogenic product when incubated with manoalide. These data suggest that lysine is capable of reacting with manoalide, but only when it is present in macromolecules is it capable of protecting phospholipase A2 from inactivation by manoalide. Because cellular proteins protect PLA2 from inactivation by manoalide, high concentrations of manoalide must be applied topically to produce statistically significant inactivation of intracellular phospholipase A2. Finally, a chemical model is presented which explains the formation of a chromogenic product when manoalide is incubated with proteins and amino acids.

Administration, Topical↗
PubMed1986

Lumbar puncture and subarachnoid haemorrhage.

Medical notes of 123 patients with subarachnoid haemorrhage were examined. No patient deteriorated at the time of lumbar puncture. All but 2 patients with associated intracerebral haematomas had markedly impaired consciousness or focal signs. Two of 30 patients with meningitis were initially diagnosed as subarachnoid haemorrhage, and one died without lumbar puncture. If consciousness is not markedly impaired and focal signs are absent, lumbar puncture is safe in patients with subarachnoid haemorrhage.

Adult↗
PubMed1986

Physiological changes after biofeedback and relaxation training for multiple-pain tension-headache patients.

This paper is concerned with the psychophysiology of "muscle-contraction" headaches in a group of Compensation patients suffering from multiple pain problems in addition to headaches. A total of 55 of these patients were divided into 4 groups which received frontalis EMG biofeedback, relaxation training, combined biofeedback-relaxation training, or no treatment. Differences were observed among the 3 experimental treatments and the control group with respect to headache changes, but there were no differences among groups with respect to the changes observed in four underlying physiological responses as a function of time or practice. While the subjects who showed the largest changes in headache characteristics were those who exhibited the largest decreases in frontalis EMG, these were also the subjects whose initial frontalis EMG levels were the highest. It is concluded that, in keeping with a growing literature, the link between frontalis EMG and "muscle-contraction" headaches is a tenuous one and that the changes brought about in headache symptomatology through biofeedback or relaxation training are most likely attributable to a generalization of feelings of mastery over the environment or of self-efficacy brought about in the subjects through apparent success at the task.

Adult↗
PubMed1986

Muscle-contraction headaches in multiple-pain patients: treatment under worsening baseline conditions.

A total of 55 muscle-contraction headache patients were divided into four groups which received frontalis EMG biofeedback, relaxation training, combined biofeedback-relaxation training, or no-treatment control. All patients were compensation patients undergoing assessment and brought to a high level of activity for the first time since going into chronicity. In all cases, onset or aggravation of the headaches coincided with the compensation-related injury. All treatment modalities led to significant but similar levels of improvement in headaches, while the control group worsened.

Adult↗