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Biomedical subjects

G T Carter

Publications and source records attributed to G T Carter.

At least 55 records · Page 3Linked to original sources
PubMed1994

Successful pregnancies in the presence of spinal muscular atrophy: two case reports.

We report two cases of successful pregnancy in women with chronic, infantile onset, or type II spinal muscular atrophy, both of whom delivered healthy, unaffected babies. The patients required concurrent management by a physiatrist, pulmonologist, and perinatologist throughout the pregnancy. Complications included recurrent urinary tract infections, dyspnea and worsening of pulmonary function, wheelchair seating and positioning problems, and musculoskeletal and low back pain. These problems resolved postpartum. One woman had vaginal delivery, the other had caesarean section, both of which were well-tolerated. Because of severe musculoskeletal deformity, pelvic assessment is necessary to determine the mode of delivery. The uterus has normal contractility and effective labor patterns can be established. Spinal/epidural anesthesia may be contraindicated because of spine deformity. The pregnancies had no deleterious effect on the progression of the disease in our patients, both of whom reported a positive experience with great personal fulfillment.

Adult↗
PubMed1992

Evaluation of phrenic nerve and pulmonary function in hereditary motor and sensory neuropathy, type I.

Phrenic nerve and diaphragmatic dysfunction has been assumed to be the cause of respiratory failure in hereditary motor and sensory neuropathy, type 1 (HMSN I). In order to determine the relationship between phrenic nerve and pulmonary function in this disease, 25 patients underwent a 4-step evaluation process consisting of: (1) bilateral phrenic nerve conduction study; (2) median, peroneal, and tibial motor conduction studies; (3) measurement of forced vital capacity (FVC) and maximal inspiratory and expiratory pressures (MIP, MEP); and (4) pulmonary-focused history and physical. Phrenic nerve motor latency was abnormally prolonged in 22 of the 23 (96%) subjects when a response was obtained. All had slowed velocity or absent peripheral motor conduction responses. Vital capacity was abnormally reduced in 6 of the 25 (24%) subjects. Eight (32%) had an abnormally reduced MIP, while 19 (76%) had an abnormally reduced MEP. Only 2 (8%) subjects had clinical evidence of pulmonary dysfunction. None of the dependent variables (FVC, MIP, MEP, peripheral nerve conduction, or clinical examination) correlated with phrenic nerve latencies. Although phrenic nerve latencies are markedly prolonged in HMSN I, these values are not useful in predicting respiratory dysfunction.

Adult↗
PubMed1992

Electromyographic and nerve conduction studies in the mdx mouse.

Electromyographic responses to needle-electrode insertion and repetitive indirect stimulation were recorded from gastrocnemius, soleus and cranial tibialis muscles of normal and dystrophic (mdx) mice at 20-154 days. Recordings from myotonic (ADRmto) mice served as controls for "true" myotonia. Complex repetitive discharges were observed in muscles of mdx mice but no complex repetitive discharges or other abnormalities were observed in muscles of normal control mice. Complex repetitive discharges in mdx muscles did not resemble the prolonged, abnormally repetitive discharges observed in myotonic mouse muscles. Neuromuscular blockade with tubocurarine and nerve transection had no effect on observed electromyographic abnormalities in the mdx mice. Nerve conduction and repetitive stimulation studies also revealed no abnormalities in mdx mice. These findings indicate that the mdx condition is a nonmyotonic, primary myopathy. No signs of myotonia or impaired neuromuscular transmission were found in mdx mice.

Animals↗
PubMed1992

Lack of effect of amitriptyline in murine myotonia.

Amitriptyline, a tricyclic antidepressant, has been reported to diminish signs of human myotonic muscular dystrophy, but has not been examined in other myotonias. Normal and myotonic (ADRmto) mice were injected acutely with either amitriptyline, phenytoin, procainamide or 0.9% saline. In addition, two groups of myotonic mice were injected chronically with either 0.9% saline or amitriptyline for 28 days. Behavior, assessed before injection using a "drop test," was re-evaluated at 30-min intervals for up to 180 min postinjection, as well as at the end of the 28-day chronic trial. If improvement in behavior was noted, the mice were then evaluated with insertional needle electromyography (EMG) and in vitro contractility (maximal tetanic tension and relaxation time) studies. Neither acute nor chronic amitriptyline administration had any beneficial effect on behavior, EMG or contractile parameters in myotonic mice. Phenytoin abolished abnormal EMG activity and improved behavior. Procainamide improved behavior and contractility parameters but had no effect on EMG. These results confirm that the myotonic mouse is responsive to classic antimyotonic agents, but not to amitriptyline.

Amitriptyline↗
PubMed1992

Laryngeal diversion in the treatment of intractable aspiration in motor neuron disease.

Motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) often causes bulbar palsy with subsequent aspiration. Laryngeal diversion procedures are not commonly mentioned in the literature. However, they are viable but infrequently used surgical treatment options that have several advantages over a routine tracheostomy. We report a case of a 67-year-old man with MND/ALS and severe aspiration. He underwent a laryngeal diversion procedure with complete relief of signs and symptoms of aspiration. Laryngeal diversion, unlike tracheostomy, completely eliminates the possibility of aspiration as well as the need for suctioning. The primary disadvantage is complete loss of phonation. These procedures appear worthy of trial in patients with MND/ALS, and may ultimately be the preferred treatment in this setting.

Aged↗
PubMed1991

The effect of methylation inhibitors on citreamicin biosynthesis in Micromonospora citrea.

When the citreamicin-producing organism Micromonospora citrea NRRL 189351 was incubated in the presence of the methylation inhibitors sinefungin or aminopterin, biosynthesis of the zeta component was stimulated approximately 20 to 200-fold above the level normally produced. Inhibition of a second methylation reaction, which is superficially very similar to the first, was not detected. Other known methylation inhibitors failed to yield any change in the natural pattern of citreamicins produced. This approach is an excellent route for preparing citreamicin zeta, which can be used as a substrate for semi-synthesis or for further biosynthetic studies.

Adenosine↗
PubMed1989

Process-scale reversed-phase high-performance liquid chromatography purification of LL-E19020 alpha, a growth promoting antibiotic produced by Streptomyces lydicus ssp. tanzanius.

LL-E19020 alpha is a novel antibiotic produced by fermentation of the soil microorganism Streptomyces lydicus ssp. tanzanius. The compound is highly effective in inducing increases in weight gain and feed conversion efficiency in livestock. In order to obtain kilogram quantities of the material for field trials, pilot plant scale fermentations (up to 7500 l) were carried out. The antibiotic was recovered from the fermentation broth by solvent extraction. The resultant crude extract was subjected to reversed-phase (C18) chromatography on a process-scale high-performance liquid chromatography (HPLC) unit. The heart of the instrumentation is the Millipore Kiloprep chromatograph with the standard 12-l cartridge column. The laboratory housing the chromatograph has been specifically designed for this work. Tanks for mobile phase preparation are mounted on load cells for precise measurement of components. In this explosion-proof laboratory, all solvent handling areas are well ventilated and a separate breathing air system is provided for the operators. For the purification of the LL-E19020 antibiotics, the mobile phase consisted of a gradient of acetonitrile in 0.1 M ammonium acetate at pH 4.5. The effluent was monitored by UV absorbance at 325 nm. Fractions were collected across the peaks of interest and these were analyzed by analytical HPLC. The maximum yield of LL-E19020 alpha obtained in a single run was approximately 100 g. The antibiotic was recovered from the mobile phase by extraction with methylene chloride. The methylene chloride phase was concentrated under reduced pressure to yield a gummy residue which was finally freeze-dried from tertiary butanol to yield an off-white solid suitable for blending with various feed components.

Aminoglycosides↗
PubMed1989

Biosynthetic origin of the carbon skeleton and oxygen atoms of the LL-F28249 alpha, a potent antiparasitic macrolide.

The biosynthesis of LL-F28249 alpha in a culture of Streptomyces cyaneogriseus has been studied using 13C, 14C and 18O labeled precursors. A complete 13C NMR spectrum of F28249 alpha has been assigned. Incorporation studies using 13C labeled precursors indicate that the carbon skeleton of F28249 alpha is derived from seven acetate, six propionate and one 2-methylpropionate units. The origin of the oxygen atoms of F28249 alpha has been examined by feeding [1-13C,18O2]acetate, [1-13C,18O2]propionate, [2-13C]acetate/18O2 and 18O2 separately to the fermentation culture and analyzing the resulting labeled LL-F28249 alpha samples by 13C NMR, electron impact MS and chemical ionization MS. Out of a total of eight oxygen atoms in LL-F28249 alpha, four oxygen atoms are derived from acetate, three from propionate and one from molecular oxygen.

Anti-Bacterial Agents↗
PubMed1988

LL-F28249 antibiotic complex: a new family of antiparasitic macrocyclic lactones. Isolation, characterization and structures of LL-F28249 alpha, beta, gamma, lambda.

A new family of antiparasitic macrolides has been isolated from Streptomyces cyaneogriseus sp. noncyanogenus. The compounds, designated LL-F28249 alpha, beta, gamma and lambda, possess potent antiparasitic activity. The isolation, purification and structure determination by spectroscopic methods are presented.

Anti-Bacterial Agents↗
PubMed1985

Biosynthesis of chrysomycins A and B. Origin of the chromophore.

The biosynthetic origin of the carbon atoms in the chromophores of chrysomycins A and B was investigated in feeding experiments using 13C labeled acetates and propionate. A biosynthetic scheme is proposed involving the condensation and rearrangement of a decaketide intermediate which contains either propionate (chrysomycin A) or acetate (chrysomycin B) as the chain initiator.

Acetates↗
PubMed1982

Peak homogeneity determination for the validation of high-performance liquid chromatographic assay methods.

To validate high-performance liquid chromatographic assay procedures with regard to specificity, methods were developed to determine the homogeneity of the chromatographic peaks. These methods employed a rapid-scanning UV-visible spectrophotometer to monitor the chromatographic effluent. The absorption data were processed to nullify the signal due to the drug substances specifically, while allowing the detection of coincident impurities. Results from three model systems indicated the ability of these methods to detect as little as 0.1% of a coincident impurity.

Biotransformation↗
PubMedDate not supplied

Plasma membrane protection against the acute effects of inorganic lead on the respiratory rates of intact liver cells.

To evaluate the acute effects of inorganic lead on oxidative metabolism in hepatocytes, intact liver cells were isolated from hamsters and incubated with solutions of PbCl2. These cells were found to be relatively resistant to respiratory inhibition as compared to liver homogenates. That is, in the presence of 1 mM PbCl2, the rate of oxygen consumption of the intact cells was approximately 6% less than that of controls. In contrast, the respiratory rates of liver homogenates treated with 1 mM PbCl2 were about 70% lower than controls. The resistance of the intact cells persisted even after 4 1/2 h of incubation with the lead and appears to reflect the protective influence of the plasma membrane.

Animals↗
PubMedDate not supplied

Profiles of neuromuscular diseases. Design of the protocol.

The purpose of this 10-yr investigation was to develop comprehensive impairment and disability profiles of the clinical characteristics of seven neuromuscular diseases: spinal muscular atrophy, hereditary motor sensory neuropathy, Duchenne muscular dystrophy, Becker's muscular dystrophy, facioscapulohumeral muscular dystrophy, limb-girdle syndrome, and myotonic dystrophy. Based on the World Health Organization's classification of disablement, as applied to neuromuscular diseases, impairment was evaluated by measurements of strength, range of motion, spine deformity, cardiac and pulmonary function, and intellectual capacity. Disability was evaluated by measures of mobility and upper extremity function, cardiopulmonary adaptations, cardiac and pulmonary complications, and psychosocial adjustment.

Clinical Protocols↗