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Biomedical subjects

H A Baker

Publications and source records attributed to H A Baker.

12 recordsLinked to original sources
PubMed1994

Severe calcific pulmonic valve stenosis and restrictive ventricular septal defect in a 64-year-old man. Results of percutaneous double balloon valvuloplasty.

The clinical and hemodynamic features of a 64-year-old symptomatic man with severe calcific pulmonic valve stenosis and restrictive ventricular septal defect are reported. Successful double balloon percutaneous pulmonic valvuloplasty immediately produced excellent symptomatic benefit and introduced expected and well tolerated hemodynamic changes. The transpulmonic valve peak systolic pressure gradient was reduced from 130 to 30 mmHg and pulmonary artery pressure increased to top normal levels acquiring normal pulse wave configuration. A left-to-right shunt, negligible prior to valvuloplasty, increased appreciably producing a pulmonary to systemic flow ratio of 1.7. Reevaluation at 5 months revealed sustained hemodynamic profile. Symptomatic benefit and tolerance to ordinary physical activities have remained excellent at 1 year follow-up.

Calcinosis↗
PubMed1992

Effectiveness of decremental diameter balloon catheters (tapered balloon).

Natural tapering of coronary arteries from larger proximal to smaller distal diameters often creates a dilemma for optimal balloon sizing during percutaneous transluminal coronary angioplasty (PTCA). To demonstrate the need for new dilating catheters suitable for tapered coronary anatomy, 100 consecutive coronary arteries were measured by videodensitometry, 1 cm proximal and distal to the stenosis. In 23 arteries there was a 1 mm or greater taper and 19 arteries showed a 0.5 to 0.99 mm taper. Only 50 arteries showed a nearly uniform diameter at the site of the stenosis, and 8 arteries demonstrated reverse taper, i.e., distal was greater than proximal diameter. To avoid balloon size mismatch with significant tapering, decremental diameter balloon catheters were developed. Series I tapers from 3.5 to 3.0 mm and series II from 3.0 to 2.5 mm over a balloon length of 25 mm. Tapered balloons were used in 80 patients with 94 tapered coronary arteries. Before PTCA, proximal, stenotic and distal mean diameters measured 3.6, 1.1 and 2.6 mm, respectively; after PTCA, proximal, stenotic and distal diameters measured 3.6, 2.8 and 2.5 mm, respectively, thus maintaining the natural tapering after effective dilatation. Only 2 arteries (2.1%) showed significant dissection, with no abrupt occlusions, and none requiring bypass surgery. In summary, decremental diameter balloon catheters provide optimal dilation in tapered arterial segments with few complications and offer a new approach to balloon sizing.

Angioplasty, Balloon, Coronary↗
PubMed1984

Dopamine synthesis in inbred mouse strains which differ in numbers of dopamine neurons.

BALB/cJ and CBA/J mice have been shown to have different numbers of dopamine (DA) neurons in the central nervous system, with BALB/cJ mice having 20-50% more DA neurons in each dopaminergic cell group which is reflected in a difference in tyrosine hydroxylase activity in these cell groups. The present study compared the levels of DA and the rate of DA synthesis between these two inbred mouse strains. Three measures were used to reflect the rate of DA synthesis: the levels of DA metabolites (DOPAC and HVA) in the striatum, the rate of disappearance of DA following inhibition of tyrosine hydroxylase with alpha-methyl-P-tyrosine, and the rate of accumulation of DOPA following inhibition of aromatic amino acid decarboxylase with NSD-1015. Striatal DA levels were slightly higher in CBA/J mice than BALB/cJ mice. The rate of DA synthesis in the striatum, as estimated from the accumulation of DOPA following NSD-1015 injection or from the decline of DA levels following alpha-methyl-p-tyrosine injection, was from 30-50% greater in the BALB/cJ mice compared to the CBA/J mice. In striatum, DOPAC levels were higher, HVA levels lower, and DOPAC plus HVA levels equal in CBA/J mice compared to BALB/cJ mice. The results show that BALB/cJ mice, with more DA neurons than CBA mice, also synthesize more DA. In addition, the data suggest that DA levels do not necessarily reflect numbers of DA neurons, and that catecholamine metabolite levels are not a good measure for comparing catecholamine synthesis between inbred animal strains.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1980

Bacterial sensitivity test kit.

A method and an apparatus have been developed for the determination of the susceptibility of pathogenic bacteria to antibiotics. The method has the same applicability as the accepted Bauer-Kirby method. The method is rapid, the procedure for the performance of the test is simple, the supplies and equipment for the performance of the test are inexpensive and finally the test gives easily measurable end-points. The correlation of the method to the accepted Bauer-Kirby method against clinical isolates of gram-positive bacteria was 90-100% for the antibiotics tested with the exception of neomycin which was 80%. With gram-negative bacteria, the correlation was 92-100% for the antibiotics tested.

Humans↗
PubMed1980

Uterine catecholamines and prostaglandins during the estrous cycle of the rat.

The uterine contents of norepinephrine, epinephrine, dopamine, and prostaglandins F and E were determined on each day of the rat estrous cycle. Catecholamines were determined by high performance liquid chromatography with electrochemical detection (HPLC-EC) as well as by a radioenzymatic technique; prostaglandins were quantitated by RIA. The norepinephrine and dopamine values obtained by the radioenzymatic assay were approximately 1.5 times as high as the values obtained by HPLC-EC (norepinephrine, 285 vs. 188 ng/g; dopamine, 11.0 vs. 7.5 ng/g). Despite this difference in levels, both analytic techniques showed a decline in uterine norepinephrine from diestrus to estrus, followed by a significant (P less than 0.01) increase in norepinephrine on the day of metestrus. A cyclic pattern was also revealed for uterine dopamine concentration. There was a decline in dopamine concentration from diestrus to proestrus (radioenzymatic, P less than 0.01), followed by a return to high levels at metestrus (HPLC-EC). Epinephrine levels were low (undetectable by radioenzymatic assay; 24 ng/g by HPLC-EC) and showed no variation during the estrous cycle. Prostaglandin F was uniformly higher than prostaglandin E (10 vs. 2.5 ng/uterus). Significant increases in the uterine contents of both prostaglandins were shown on the day of proestrus.

Animals↗
PubMed1979

Disinfection of anesthesia and respiratory therapy equipment with acid glutaraldehyde solution.

The dilution of acid glutaraldehyde solution and its effect on microbiological effectiveness were investigated using Sonacide and the Cidematic Decontamination System under normal use conditons at 18 hospitals over a 4-week period. The dilution of Sonacide was found to follow first-order kinetics and is described by the equation, ln C = ln Co-KT, where K is the apparent dilution-rate constant. The average dilution-rate constant under normal use conditions was 0.015/day. It takes an average of 47 days under normal hospital-use conditions to reduce its potency to half its original strength. The average glutaraldehyde concentration after 28 days' use was found to be approximately 66% of the initial concentration. The AOAC use-dilution test was employed to evaluate the microbiological effectiveness of the Sonacide samples collected weekly for four weeks. Results showed that all the Sonacide samples from 18 hospitals passed the AOAC use-dilution test for Pseudomonas aeruginosa (ATCC 15442). Based on this study, it is apparent that Sonacide can be used to disinfect various anesthesia and respiratory therapy equipment for up to 4 weeks in the Cidematic machine.

Aldehydes↗
PubMed1977

Histochemical and biochemical characterization of the rat paracervical ganglion.

The nature and identity of the catecholamines in the paracervical ganglion and superior cervical ganglion small, intensely fluorescent (SIF) cells were investigated using fluorescence histochemical and immunohistochemical techniques. The paracervical ganglion SIF cells were found to contain norepinephrine and the superior cervical ganglion SIF cells, dopamine. The norepinephrine content of the paracervical ganglion SIF cells averaged about 72 ng/ganglion and did not change during the rat estrus cycle. The activity of the enzyme tyrosine hydroxylase in the PCG was very low (about 0.48 nmoles DOPA formed/h/mg protein) and was about 1/50th of the activity of the enzyme in the SCG, where it averaged about 23.90 nmoles DOPA formed/h/mg protein. These experiments suggested that the paracervical ganglion has large numbers of norepinephrine containing SIF cells with a relatively slow turnover of their catecholamine content.

Adrenal Medulla↗
PubMed1976

Comparison of antimicrobial activity of nuclear-substituted aromatic esters of 5-dimethylamino-1-phenyl-3-pentanol and 3-dimethylamino-1-phenyl-1-propanol with related cyclic analogs.

A series of six aromatic esters of both 5-dimethyl-amino-1-phenyl-3-pentanol and 3-dimethylamino-1-(2-phenylcyclohexyl)-1-propanol was prepared. Antimicrobial evaluation showed that the cyclic analogs had approximately twice the activity of the open chain series; in particular, the o-chlorophenyl ester showed pronounced activity against three pathogenic fungi at approximately 10 ppm. Aromatic esters of 3-dimethylamino-1-phenyl-1-propanol were prepared and demonstrated lower activity than two esters of 2-dimethylamino-1-phenylcyclohexanol. The screening results showed that the best activity was found when a dimethylene chain was present between the phenyl ring and the carbon atom bearing the acyloxy function and that the cyclic derivatives were more active than their more flexible counterparts.

Amino Alcohols↗
PubMed1975

Antimicrobial evaluation of diastereoisomeric 2-dimethylaminomethyl-6-phenylcyclohexanols and related esters.

2-Dimethylaminomethyl-6-phenylcyclohexanone was reduced to give the isomeric 2-dimethylaminomethyl-6-phenylcyclohexanols, which were then converted to a number of novel esters. These derivatives were screened against a wide range of microorganisms. The alcohol possessing an axial hydroxy group had high activity against Candida albicans, in contradistinction to the isomer having an equatorial hydroxy function, which was approximately 30 times less active. The esters from the isomeric alcohols demonstrated a low level of antimicrobial activity with the exception of the 10-undecenoyl ester of 2-dimethylaminomethyl-6-phenylcyclohexanol (possessing the equatorial hydroxy group), which showed significant activity against three pathogenic fungi.

Animals↗
PubMed1975

Naphthyridinomycin, a new broad-spectrum antibiotic.

A new antibiotic, naphthyridinomycin, was isolated in crystalline form from the culture filtrate of Streptomyces lusitanus AY B-1026. The antibiotic is active against a large number of both gram-positive and gram-negative bacteria, and inactive against Candida albicans, Trichophyton granulosum and Microsporum gypseum. The antibiotic is toxic in mice.

Animals↗