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Biomedical subjects

S F Hoffman

Publications and source records attributed to S F Hoffman.

7 recordsLinked to original sources
PubMed1979

Rapid metabolism of phenytoin: a method of calculating proper dosage.

The optimal dosage of phenytoin can be accurately determined by a pharmacokinetic method. By plotting the rate of administration of phenytoin acid against the apparent plasma clearance rate, we estimated the maximum rate of metabolism and the serum concentration at which the rate of metabolism was one half the maximum rate for phenytoin and then applied the Michaelis-Menten equation to optimize the dosage of phenytoin in a 48-year-old man with uncontrolled idiopathic generalized seizures and increased metabolism of phenytoin. The patient became seizure free on a regimen of 650 mg of phenytoin daily and experienced no side effects of phenytoin over-dosage. The pharmacokinetic technique described is simple to use and can be applied in an outpatient clinic.

Dose-Response Relationship, Drug↗
PubMed1977

Individualization of phenytoin dosage regimens.

Two methods for arriving at optimum, individual phenytoin dosage regimens have been evaluated in 12 patients. (1) Individual Michaelis-Menten pharmacokinetic parameters for phenytoin were estimated from two reliable steady-state phenytoin serum concentrations resulting from different daily doses: The observed steady-state phenytoin serum levels obtained after 3 to 8 wk of compliance with dosage regimens calculated from the individual pharmacokinetic parameters agreed well with predicted levels (r = 0.824, p less than 0.02). The average deviation between observed and predicted levels was 0.04 mug/ml (range, +/- 3.2 mug/ml). (2) A previously published nomogram for making adjustments in phenytoin dosage regimens: The serum phenytoin concentration actually expected from the dose indicated by the nomogram was calculated using individual pharmacokinetic parameters. The daily dose for one patient would have exceeded his estimated maximal rate of metabolism. The correlation between calculated and predicted phenytoin serum levels in the other 11 patients was weak but significant (r= 0.360, p less than 0.05). The average deviation was --3 mug/ml (range, 3.9 to --11.3 mug/ml). It was concluded that the use of individual pharmacokinetic parameters is practical and is also superior to the nomogram.

Adolescent↗
PubMed1975

Cerebral cysticercosis.

Cerebral cysticercosis is a neurologic disease with myriad manifestations. Three basic types of infections occur: localized, widespread, and proliferative inflammatory reaction. A case is reported illustrating the first type of infection and one type of clinical presentation,--focal seizures. The worldwide distribution of the disease suggests that as global travel increases we will have to consider the diagnosis more often. The diagnosis is established principally through thorough examination of the CSF plus signs of parasitosis in other parts of the body. A history of living in an endemic area should strengthen suspicion. Definitive treatment is currently limited to neurosurgical intervention.

Adult↗
PubMed1971

On finding striated muscle in the brain.

Well-developed striated muscle was found in the leptomeninges of a 2 day old infant with a 13-15 trisomy defect and multiple congenital anomalies. Except for arhinencephaly, minor sulcal abnormalities, and scattered microscopic cerebellar dysplasias the brain was well formed. The extreme rarity of this finding is noted and an attempt is made to explain it on an embryological basis. The implications of this observation in relation to some central nervous system tumours containing striated muscle are briefly discussed.

Abnormalities, Multiple↗
PubMedDate not supplied

Infection and disease induced in chimpanzees with 6/94, a parainfluenza type 1 virus isolated from human multiple sclerosis brain.

A parainfluenza type 1 virus (6/94) recovered from brain cell cultures of two patients with multiple sclerosis (MS) was inoculated into newborn chimpanzees by the intranasal (IN) or intracerebral (IC) routes. Four of the five animals receiving the virus IN developed clinical signs ranging from mild fever, with or without rhinorrhea, to severe respiratory disease. Two of the chimpanzees died as a result of pneumonia. Virus could be recovered from respiratory tracts for as long as 9 days after exposure and was followed by development of specific neutralizing antibody to the 6/94 virus but not to the HA2 strain of parainfluenza type 1. Brain examination showed astrocytosis, especially of posterior fossa structures, activation of microgliacytes and, in one animal, round cell infiltration of leptomeninges. Of thse three animals receiving virus IC, two developed recurrent seizures beginning 14 months after inoculation. One of these was sacrificed at 23 months of age after progressive neurologic disease, with electroencephalographic abnormalities, developed. The third animal died at 3 months of age of intercurrent pneumonia. No virus was recovered from these animals, although all showed antibody conversion to 6/94 but not HA2 virus. A variety of pathologic lesions were seen in the brains of both animals coming to necropsy particularly in the sacrificed chimpanzee. These included subacute encephalitis, extensive cortical and subcortical degeneration, vascular sclerosis, white matter gliosis and axonal dystrophy.

Animals↗