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Biomedical subjects

R Lovelace

Publications and source records attributed to R Lovelace.

9 recordsLinked to original sources
PubMed1996

Myelin protein zero (MPZ) gene mutations in nonduplication type 1 Charcot-Marie-Tooth disease.

The myelin protein zero gene (MPZ) maps to chromosome 1q22-q23 and encodes the most abundant peripheral nerve myelin protein. The Po protein functions as a homophilic adhesion molecule in myelin compaction. Mutations in the MPZ gene are associated with the demyelinating peripheral neuropathies Charcot-Marie-Tooth disease type 1B (CMT1B), and the more severe Dejerine-Sottas syndrome (DSS). We have surveyed a cohort of 70 unrelated patients with demyelinating polyneuropathy for additional mutations in the MPZ gene. The 1.5-Mb DNA duplication on chromosome 17p11.2-p12 associated with CMT type 1A (CMT1A) was not present. By DNA heteroduplex analysis, four base mismatches were detected in three exons of MPZ. Nucleotide sequence analysis identified a de novo mutation in MPZ exon 3 that predicts an Ile(135)Thr substitution in a family with clinically severe early-onset CMT1, and an exon 3 mutation encoding a Gly(137)Ser substitution was identified in a second CMT1 family. Each predicted amino acid substitution resides in the extracellular domain of the Po protein. Heteroduplex analysis did not detect either base change in 104 unrelated controls, indicating that these substitutions are disease-associated mutations rather than common polymorphisms. In addition, two polymorphic mutations were identified in MPZ exon 5 and exon 6, which do not alter the codons for Gly(200) and Ser(228), respectively. These observations provide further confirmation of the role of MPZ in CMT1B and suggest that MPZ coding region mutations may account for a limited percentage of disease-causing mutations in nonduplication CMT1 patients.

Adult↗
PubMed1990

Hereditary induced peripheral neuropathies.

The hereditary neuropathies, representing up to 20 per cent of the total of peripheral neuropathies, present a considerable problem in neurology, rehabilitation medicine, and orthopedics. Patients have predominant foot abnormalities such as pes cavus and talipes equina varus. The largest section is the Charcot-Marie-Tooth syndrome or peroneal muscular atrophy, followed by the leucodystrophies and adrenal myloneuropathy. Information is burgeoning with the advent of molecular genetics, and we anticipate therapeutic options when gene products are discovered.

Biopsy↗
PubMed1988

Physiologic and anatomic basis for contralateral R1 in blink reflex.

We studied the rate of appearance and mechanism of contralateral R1 responses in normal subjects. Contralateral R1 could be produced by facilitating maneuvers such as a gentle contraction of the orbicularis oculi and conditioning stimulus of the median nerve. In addition, changing the position of the stimulating anode to the midline evoked these responses that were abolished by blocking the contralateral supraorbital nerve, confirming its peripheral origin. We conclude that crossed trigeminofacial pathways probably exist in normal subjects, but in some instances contralateral peripheral trigeminal ophthalmic sensory fibers may be stimulated, giving rise to a contralateral R1 response.

Blinking↗
PubMed1983

Case report of carpal tunnel syndrome associated with tranylcypromine.

A man who developed carpal tunnel syndrome while taking tranylcypromine was treated with 300 mg/day of pyridoxine, which resulted in significant improvement. The authors discuss the two major mechanisms by which monoamine oxidase inhibitors can inactivate pyridoxine.

Carpal Tunnel Syndrome↗
PubMed1979

Muscle carnitine deficiency. Genetic heterogeneity.

Two types of lipid storage myopathy have been associated with decreased content of carnitine in muscle. In "muscle carnitine deficiency", carnitine concentration is normal in serum, but reduced in muscle. In "systemic carnitine deficiency", apparently due to imparied synthesis of carnitine in the liver, carnitine content is low in both serum and muscle. We studied a woman with a corticosteroid-responsive, probably autosomal recessive, lipid storage myopathy. Carnitine therapy was ineffective and carnitine failed to correct the impaired fatty acid oxidation in muscle homogenates, in contrast to a previous case. Carnitine transport into skeletal muscle was normal. These observations suggest that ll cases of "muscle carnitine deficiency are not the same.

Adult↗
PubMed1972

Multiple sclerosis associated with defects in neuromuscular transmission.

Three patients with multiple sclerosis characterized by exacerbations and remissions of nervous system signs and symptoms disseminated in time and space also had the kind of easy fatiguability seen in myasthenia gravis. In each case abnormal decrements to repetitive stimulation were electromyographically demonstrated and treatment with ephedrine or anticholinesterase drugs increased the patient's functional capacity while improving the electromyographic abnormality. The suggestion is that these patients represent an overlap syndrome, analogous to the overlap syndrome existing between systemic lupus erythematosus and rheumatoid arthritis where clinical and laboratory features of two diseases coexist in the same patient at the same time. Presumably some patients with multiple sclerosis have deficient production of acetylcholine, just like patients with myasthenia, and treatment with agents useful in myasthenia is able partially to correct the symptoms caused by the deficiency. The cases illustrate how in neurology greater attention to the more immediate cause of clinical symptoms, in the absence of a known aetiology, may result in benefit to the patients.

Adult↗