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Biomedical subjects

M A McLaughlin

Publications and source records attributed to M A McLaughlin.

32 records · Page 2Linked to original sources
PubMed1991

Thermodynamics of hydrolysis of oligosaccharides.

Microcalorimetry has been used to determine enthalpy changes for the hydrolysis of a series of oligosaccharides. High-pressure liquid chromatography was used to determine the extents of reaction and to check for any possible side reactions. The enzyme glucan 1,4-alpha-glucosidase was used to bring about the following hydrolysis reactions: (A) maltose(aq) + H2O(liq) = 2D-glucose(aq); (B) maltotriose(aq) + 2H2O(liq) = 3D-glucose(aq); (C) maltotetraose(aq) + 3H2O(liq) = 4D-glucose(aq); (D) maltopentaose(aq) + 4H2O(liq) = 5D-glucose(aq); (E) maltohexaose(aq) + 5H2O(liq) = 6D-glucose(aq); (F) maltoheptaose(aq) + 6H2O(liq) = 7D-glucose(aq); (G) amylose(aq) + nH2O(liq) = (n + 1) D-glucose(aq); and (H) panose(aq) + 2H2O(liq) = 3D-glucose(aq); (J) isomaltotriose(aq) + 2H2O(liq) = 3D-glucose(aq). The enzyme beta-fructofuranosidase was used for the reactions: (K) raffinose(aq) + H2O(liq) = alpha-D-melibiose(aq) + D-fructose(aq); and (L) stachyose(aq) + H2O(liq) = o-alpha-D-galactopyranosyl-(1----6)- alpha-o-D-galactopyranosyl-(1----6)-alpha-D-glucopyranose + D-fructose(aq). The results of the calorimetric measurements (298.15 K, 0.1 M sodium acetate buffer, pH 4.44-6.00) are: delta H0A = -4.55 +/- 0.10, delta H0B = -9.03 +/- 0.10, delta H0C = -13.79 +/- 0.15, delta H0D = -18.12 +/- 0.10, delta H0E = -22.40 +/- 0.15, delta H0F = -26.81 +/- 0.20, delta H0H = 1.46 +/- 0.40, delta H0J = 11.4 +/- 2.0, delta H0K = -15.25 +/- 0.20, and delta H0L = -14.93 +/- 0.20 kJ mol-1. The enthalpies of hydrolysis of two different samples of amylose were 1062 +/- 20 and 2719 +/- 100 kJ mol-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylose↗
PubMed1988

Monitoring the quality of contracted therapy services provided by a vendor: a model for home health services.

Many home health care agencies contract with outside vendors to provide some services, such as occupational and physical therapy. The agency, however, must assure the quality of these contracted services. Rush Home Health Service has developed a system for monitoring the quality of care provided by a vendor of rehabilitation services. The system focuses on seven aspects of care provided by the vendor: referral response time, contract therapists' records, visit attempts, timeliness of documentation, presence of required documentation, content of documentation, and the quality of care (goals reached, continuity of care, and patient satisfaction).

Chicago↗
PubMed1985

A synopsis of recent developments in antiglaucoma drugs.

Open-angle glaucoma is treated primarily with drugs, some of which have been used clinically for years. These drugs include: 1) cholinergic agonists that increase aqueous humor outflow, 2) adrenergic agonists and antagonist that affect both aqueous humor formation and outflow, and 3) carbonic anhydrase inhibitors that decrease aqueous humor formation. Several new classes of drugs are being tested for efficacy and mechanism of action. They include: 1) the D-isomer of timolol that reduces aqueous humor formation without producing adrenergic blockade, 2) dopaminergic agonists and antagonists, including bromocriptine and butyrophenones that reduce intraocular pressure, and 3) cannabinoids that reduce aqueous humor formation and increase outflow. In addition, several other types of drugs, such as prostaglandins, diuretics, Na+,K+-ATPase inhibitors, and adenyl cyclase stimulators are just now beginning to be studied.

Cannabinoids↗
PubMed1985

Existence and role of endogenous ocular melatonin.

The proposed role of melatonin as an endogenously synthesized modulator of intraocular pressure in the eye was investigated. Melatonin levels were determined by radioimmunoassay in the iris, ciliary body and retina-choroid of pinealectomized or sham-operated chickens by day and by night. Pinealectomy had no effect on melatonin levels in the ciliary body or retina of chicken eyes; a diurnal rhythm continued to be observed in these tissues, with values higher by night than by day. Chloroform-extracted melatonin levels in the rabbit ciliary body showed a diurnal rhythm but melatonin levels in rabbit retina did not. Intracameral infusion of melatonin into cat eyes caused aqueous humor synthesis to decrease but caused a greater decrease in aqueous humor outflow facility, leading to a significant increase in intraocular pressure. The results suggest that melatonergic mechanisms in the eye could be responsible for the diurnal rhythm in IOP, and the synthesis and diurnal rhythm of this melatonin are independent of the pineal gland.

Animals↗
PubMed1985

Are beta-adrenergic mechanisms involved in ocular hypotensive actions of adrenergic drugs?

Specific beta 1- and beta 2-adrenergic agonists and antagonists were studied for their effects on aqueous humor dynamics in a cat model. Tazolol (beta 1-agonist) reduced formation of aqueous humor more than outflow, while metoprolol (beta 1-antagonist) reduced outflow more than formation. Both salbutamol (beta 2-agonist) and butoxamine (beta 2-antagonist) inhibited aqueous humor formation and aqueous humor outflow to an equal extent. It is concluded that the adrenergic mechanism is functioning only slightly, if at all, in affecting the intraocular pressure. On the other hand, receptor binding experiments on iris-ciliary body showed clearly that there are 40-fold and 281-fold differences in binding affinity of D- and L-isomers of timolol and propranolol, respectively. These results indicate that the adrenergic receptor mechanism does exist in the eye tissues but that it does not control intraocular pressure significantly.

Adrenergic beta-Agonists↗
PubMed1985

Timolol and pilocarpine are hypotensive in light-induced avian glaucoma.

Two antiglaucoma drugs were tested on Hubbard chicks with light-induced avian glaucoma (LIAG). This animal model for open-angle glaucoma was further assessed by a novel method for monitoring aqueous inflow and outflow simultaneously. When the chicks were 8 to 9 weeks of age the preglaucomatous eyes were significantly enlarged (p less than 0.001), weighing a mean of 3.37 g, compared with 2.59 g for a group of normal eyes, but the intraocular pressure (IOP) was slightly lower in the former (13.79 v. 16.46 mm Hg; p less than 0.05). At this age the aqueous outflow was markedly reduced (to 0.70 v. 2.47 microL/min; p less than 0.05), but no change in aqueous inflow could be demonstrated. By 18 to 20 weeks the glaucomatous eyes were further enlarged (mean weight 4.67 v. 3.76 g; p less than 0.001) and hypertensive (mean IOP 29.85 v. 22.27 mm Hg; p less than 0.05). Timolol elicited a 29% to 33% reduction in the IOP at 8 to 9 weeks in both groups of eyes. At 18 to 20 weeks it reduced the IOP of the glaucomatous eyes to normal values but caused a less marked reduction in the normal eyes. Pilocarpine elicited an initial sharp rise in the IOP but was ultimately hypotensive, causing about a 33% decrease from the preinfusion IOP, in both young and adult birds.

Animals↗
PubMed1984

Studies on the involvement of melatonergic mechanism in intraocular pressure regulation.

It has been reported that diurnal changes in intraocular pressure (IOP) may be related to the fluctuation of melatonin levels in the eye. In order to test this hypothesis, effects of methysergide, tranylcypromine, and p-chlorophenylalanine (PCPA) on IOP recovery were studied in rabbits infused with hypertonic saline. Methysergide, a serotonin blocker at receptor sites, did not affect IOP recovery, presumably because it did not affect melatonin synthesis. Tranylcypromine, a monoamine oxidase inhibitor which preserves serotonin and eventually increases the level of melatonin in tissues, facilitated IOP recovery. PCPA, known to inhibit serotonin synthesis and to lower the melatonin level in tissues, markedly delayed IOP recovery. These results indicate that a chemical which decreases melatonin content in the eye also lowers the IOP and vice versa. It is suggested that some melatonergic mechanism is involved in the circadian rhythm of IOP.

Animals↗
PubMed1984

Establishment of cell lines of uveal melanoma. Methodology and characteristics.

Six continuous cell lines have been established from choroidal and ciliary body melanomas. These lines have been maintained in culture for at least 100 in vitro population doublings for periods over 1 year. They were established initially using a human diploid fibroblast strain MRC-5 as a feeder layer. Cells were grown in Ham's F-12 medium containing fetal bovine and horse sera and supplemented with glucose, cholera toxin, and epidermal growth factor. Culture doubling times ranged from 72-96 hr; cloning efficiencies ranged from 1-5% in the absence of a feeder layer. Six cell lines were studied in detail by electron microscopy, and all were found to have evidence of melanosomes and/or premelanosomes. The morphology of the cells was characteristic of melanomas as defined by the Callender classification, with cell types ranging from spindle A to epithelioid. Karyotypic studies revealed the presence of only human chromosomes with modal numbers ranging from 48-54 in the different lines.

Adult↗
PubMedDate not supplied

Exercise in the healthy older adult.

Habitual exercise provides numerous health benefits to the older adult. While dynamic aerobic activities increase stamina and lung capacity, isometric or resistance training improves muscle strength and endurance. Long-term benefits of continued exercise include a decreased risk of death from heart disease, enhanced balance and mobility, a decreased risk of diabetes, and an improvement in depressive symptoms. While the hazards of exercise relate predominantly to extremes of intensity and duration, all older adults should consult with a physician before beginning a new activity program. A prescription for exercise should include both aerobic and resistance training components, and frequent follow-up to improve adherence is highly recommended.

Adult↗
PubMedDate not supplied

Identification of hydrolyzed inulin syrup and high-fructose corn syrup in apple juice by capillary gas chromatography: PVM 4:1999.

A peer-verified, gas chromatographic (GC) method is presented for the identification of hydrolyzed inulin syrup (HIS) and high-fructose corn syrup (HFCS) in apple juice. The procedure involves determining the Brix value of the apple juice or apple juice concentrate and preparing a dilution of the test sample to 5.5 degrees Brix. A 100 microL aliquot of the 5.5 degrees Brix test solution is then freeze-dried in a GC autosampler vial. The sugars in the freeze-dried residue are converted to trimethylsilyl derivatives, by the addition of an appropriate silylation reagent, and the vial is heated at 75 degrees C for 30 min. After derivatization, the solution is introduced into a gas chromatograph where the analytes are separated on a 30 m, 0.25 mm id DB-5 column. The method can use hydrogen, helium, or nitrogen as the carrier gas. The analytes and marker compounds are measured by use of a flame ionization detecone of the 2 syrups at 2 levels. Dilution was ascertained by the presence of retrograde sugar markers found in the 2 sugar syrups. All 3 laboratories involved in the study were able to identify the correct diluent in the blind, randomly coded, apple juice test portions. The levels of dilution in the test portions were 0, 6.9% (HIS), 16.0% (HIS), 8.1% (HFCS), and 17.0% (HFCS). No false positive results were reported. Quantitative conclusions can be drawn when the same syrup is used for dilution and as a reference standard.

Beverages↗