Short communication: determination of inulin in milk using high-performance liquid chromatography with evaporative light scattering detection.

The objective of this study was to develop an HPLC method for the determination of inulin in a dairy matrix. Inulin is often added to dairy products to act as a source of dietary fiber as well as to provide technological functionality (e.g., water-holding or fat-replacing functions). The method includes hydrolysis of inulin with inulinase enzyme and determination of released fructose and glucose by HPLC coupled with evaporative light scattering detection, using water as the mobile phase. The effect of the milk background was investigated, preparing standards in milk, whey, or permeate and subjecting them to inulinase treatment. The developed method showed satisfactory linearity (R(2)=0.98 for glucose and 0.99 for fructose), good repeatability (relative standard deviation, RSD, ranging from 2.2 to 7.3% for glucose and from 0.6 to 2.3% for fructose), satisfactory reproducibility (RSD from 8.1 to 12.9% for glucose and from 3.1 to 4.9% for fructose), and good recovery (98.4 to 103.6%).

Rheological properties of rennet gels containing milk protein concentrates.

Different milk protein concentrates (MPC), with protein concentrations of 56, 70, and 90%, were dispersed in water under different treatments (hydration, shear, heat, and overnight storage at 4 degrees C), as well as in a combination of all the treatments in a factorial design. The particle size distribution of the dispersions was then measured to determine the optimal conditions for the dispersion. Heating at 60 degrees C for 30 min with 5 min of shear was chosen as the best condition to dissolve MPC powders. The samples were also characterized for composition, presence of protein aggregates, and ratio of calcium to protein. The total calcium present in MPC increased with increasing concentration of protein; however, the total calcium-to-protein ratio was lower in MPC90 than in MPC56 and MPC70. The level of whey protein denaturation, the presence of kappa-casein-whey protein aggregates in the supernatant after centrifugation, and the amount of caseins dissociated from the micelle increased as the protein concentration in the powder increased. The total amount of casein macropeptide released was lower in samples from powders with a higher protein concentration than for MPC56 or the skim milk control. The gelation behavior of reconstituted MPC was tested in systems dispersed in water (5% protein) as well as in systems dispersed in skim milk (6% protein). The gelation time of MPC dispersions was considerably lower and the gel modulus was higher than those of reconstituted skim milk with the same protein concentration. When MPC dispersions were dialyzed against skim milk, a significant decrease in the gelation time and modulus were shown, with a complete loss of gelling functionality in MPC90 dispersed in water. This demonstrated that the ionic equilibrium was key to the functionality of MPC.

Quality of life and relative importance: a comparison of time trade-off and conjoint analysis methods in patients with age-related macular degeneration.

AIM: To investigate the relative priorities in quality of life (QoL) in patients with age-related macular degeneration (AMD). METHODS: Measures of visual function, QoL and utility associated with visual loss were obtained from 122 patients with AMD classified according to macular morphology. The two methods of utility assessment were time trade-off (TTO) and conjoint analysis (CA), which have been recommended by the UK's National Institute of Clinical Excellence as techniques for the assessment of healthcare priorities. RESULTS: Results show that the two methods for assessing utility are poorly related: TTO relates moderately to visual function and disease severity but CA does not. CA identified two different subgroups of patients: one with outdoor mobility and the other with reading as their main priority. CONCLUSION: Further work is needed and caution required in interpreting data obtained using these methodologies for determining their relative importance in vision-related QoL studies.

Comparison of ion-specific electrode and high performance liquid chromatography methods for the determination of iodide in milk.

Two methods for the determination of I- in raw and processed milk were examined. A simple ion-specific electrode (ISE) method was compared against a more complex HPLC reference technique. Accuracy and precision were evaluated both within and between the 2 methods. Both methods yielded good recoveries for Ion spiked samples, ranging from 87 to 114% for ISE and 91 to 100% for HPLC. Within-run repeatability and between-run reproducibility were superior with the HPLC method, but were still more than acceptable with the ISE technique. Overall agreement of paired results between ISE and HPLC methods was good (r2 = 0.85 on raw herd milk; r2 = 0.84 on processed milk). The ISE method had a significant positive bias relative to the HPLC reference method. Both methods lend themselves well to the measurement of I- in raw or processed milk. Given its relatively low cost and ease of use, the ISE method is well suited as a screening method. The impressive accuracy, precision, selectivity, and limit of detection of the HPLC technique make it an ideal confirmation method.

Medical hazards of the tear gas CS. A case of persistent, multisystem, hypersensitivity reaction and review of the literature.

A 30-year-old incarcerated man was sprayed with the "tear gas" ortho-chlorobenzylidene malononitrile (CS). He was hospitalized 8 days later with erythroderma, wheezing, pneumonitis with hypoxemia, hepatitis with jaundice, and hypereosinophilia. During the subsequent months he continued to suffer from generalized dermatitis, recurrent cough and wheezing consistent with reactive airways dysfunction syndrome, and eosinophilia. These abnormalities responded to brief courses of systemic corticosteroid but recurred off therapy. The dermatitis resolved gradually over 6-7 months, but the patient still had asthma-like symptoms a year following exposure. Patch testing confirmed sensitization to CS. The mechanism of the patient's prolonged reaction is unknown but may involve cell-mediated hypersensitivity, perhaps to adducts of CS (or a metabolite) and tissue proteins. This is the first documented case in which CS apparently caused a severe, multisystem illness by hypersensitivity rather than direct tissue toxicity. Both the ethics and safety of CS use remain controversial, in part because of the difficulty documenting sporadic injuries received in the field, and also because the charged circumstances surrounding CS use may lead to both underreporting and exaggerated claims of medical harm. The medical literature on CS focuses mainly on its immediate irritant effects and on transient dermal and ocular injuries, with only 2 prior case reports of acute lung injury related to CS exposure. Given the paucity of documented lasting effects despite its widespread use for more than 3 decades, CS appears to be safe when deployed (outdoors) in a controlled manner, but it can cause important injuries if misused or if applied to a sensitized individual.

Altered water metabolism in tuberculosis: role of vasopressin.

PURPOSE: Patients with hyponatremia due to tuberculosis have shown variable responses to water loading in previous small studies, ranging from persistent antidiuresis to a normal diuresis. Although tuberculosis is considered a cause of the syndrome of inappropriate antidiuretic hormone secretion (SIADH), circulating vasopressin has been documented in only a few cases. We studied a larger group of patients to determine whether it can be suppressed by a short-term reduction in osmolality. PATIENTS AND METHODS: Twenty-eight hyponatremic patients (mean age +/- SD: 40 +/- 10 years) with pulmonary or miliary tuberculosis underwent a clinical evaluation, measurement of blood and urine chemistry values, and (in 22) a water load of 20 mL/kg. Volume status was evaluated by urine sodium concentration, blood and urine urea nitrogen, and plasma renin activity. Endocrine, renal, and other recognized causes of SIADH were excluded. RESULTS: All 22 patients exhibited a decline in urine osmolality and an increase in free water clearance after water loading. Water excretion was fully normal in seven of 22, with the remainder showing variable impairment of diluting ability and/or volume excreted. Plasma vasopressin, measured in 11 of 22 patients as well as in six others not subjected to water loading, was detectable despite hypo-osmolality in 16 of 17. Vasopressin levels declined after water loading, from 1.85 +/- 1.32 to 0.77 +/- 0.25 pg/mL (p less than 0.05). The majority of patients had the euthyroid sick syndrome but normal adrenal responses to cosyntropin. Although several patients had mild volume depletion when studied, this factor did not appear to explain the defect in water excretion. Hyponatremia resolved predictably within days to weeks of antituberculous therapy. CONCLUSIONS: Circulating vasopressin remains detectable in hyponatremic patients with tuberculosis and is responsive to changes in osmolality. A downsetting of osmoregulation induced by active tuberculosis ("reset osmostat") could explain this abnormality, but we cannot exclude an unidentified non-osmotic stimulus that can be counteracted by water loading.

Serum lactate dehydrogenase (LDH) in Pneumocystis carinii pneumonia, tuberculosis, and bacterial pneumonia.

An increase in serum lactate dehydrogenase (LDH) activity is commonly taken to support the presumptive diagnosis of Pneumocystis carinii pneumonia (PCP), although the LDH level may also be increased in other lung infections and in a variety of extrapulmonary disorders. To assess its diagnostic value in patients with fever, lung infiltrates, and a high prevalence of HIV infection, we compared LDH levels in 42 hospitalized patients with PCP, 71 with disseminated tuberculosis (TB), 40 with pulmonary TB, and 37 with bacterial pneumonia. Peak LDH level was higher (p < 0.05) in patients with PCP (547 +/- 157 U/L) and disseminated TB (569 +/- 338 U/L) than in patients with pulmonary TB (258 +/- 66 U/L) or bacterial pneumonia (331 +/- 139 U/L). However, substantial overlap between groups limited its diagnostic value for individual patients. Expressing LDH as its ratio to simultaneous serum aminotransferases (AST or ALT) did not enhance its discriminatory value. Most patients in each group had abnormalities in other serum enzymes (AST, ALT, alkaline phosphatase, gamma-glutamyltransferase), making an isolated elevation of LDH level uncommon (21% of PCP cases). Serum LDH has a high sensitivity for PCP (100% in this series) but must be interpreted with caution given its lack of specificity.

Short-term entrainment of ventilation to the walking cycle in humans.

We describe a breath-by-breath method to test for entrainment of breathing and walking cycles. Thirty-eight normal subjects walked comfortably on a treadmill while breathing through a pneumotachograph. We analyzed the time intervals between heel strikes and the onset of inspiration (or expiration) for evidence of phase locking between steps and breaths, using Monte Carlo simulation to model the probability that n consecutive inspirations (or expirations) would begin at a constant time interval +/- 0.10 s from heel strikes by chance. We developed empirical criteria for rhythm synchronization during series of four or more breaths, while maintaining an estimated specificity of 95%. The majority of subjects showed some evidence of entrainment (29 +/- 23% of breaths on average), which occurred intermittently, usually lasting less than 10 breaths at a time. The precision of phase locking during spontaneous entrainment was similar to that in 10 subjects who attempted to maintain deliberate entrainment. The results suggest that the walking cadence provides a persuasive, but not dominant, input to the central breathing pattern generator. The present method can detect entrainment even when it occurs sporadically or with varying coupling pattern.

Cataract: the relation between myopia and cataract morphology.

The association between high myopia and cataract is already well established and an association between simple myopia and cataract has been suggested, but it has not been clear to what extent the myopia precedes the cataract or is the result of it. The present study compares the refraction of a group of 100 British patients at the time of first presentation with cataract in whom the refraction was also known four years previously, with a group of matched controls in whom the refraction was also known four years previous to presentation. The study shows that simple myopia does not appear to predispose to cataract. It is the development of the cataract itself, in particular nuclear sclerosis, which causes the refractive change towards myopia. The myopic change precedes the development of cataract, and patients over the age of 55 showing a myopic change in refraction have a very high probability of developing nuclear sclerotic cataract. The healthy aging eye and eyes with cortical cataract or subcapsular cataract, but without nuclear sclerosis, continue to show a gradual hypermetropic change with time.

Laser treatment of primary ring-shaped epithelial iris cyst.

This is the first report of a ring-shaped, primary cyst of the iris pigment epithelium. The patient, a 28-year-old woman, presented with angle closure glaucoma. Ocular pressure was controlled medically, and the iris cyst was treated by argon laser photocoagulation. The derivation of the cyst, differential diagnosis, and mechanism of angle closure glaucoma are discussed.

Is cataract surgery justified in patients with age related macular degeneration? A visual function and quality of life assessment.

AIMS: To determine whether patients with age related macular degeneration (ARMD) benefit from cataract surgery in terms of visual function and quality of life measures, and to assess the impact of surgery on the progression of ARMD. METHODS: A prospective study was carried out of patients with and without ARMD undergoing cataract surgery. Data were collected from 187 patients at the Princess Alexandra Eye Pavilion, Edinburgh and the Oxford Eye Hospital, Oxford. The patients were divided into three groups: (1) a control group with ARMD and no surgery (n=41), (2) a study group of patients with ARMD who underwent cataract surgery (n=90), and (3) a second control group of patients without ocular comorbidities who underwent cataract surgery (n=56). Visual function and quality of life assessments were carried out at baseline and 3-5 months after baseline or surgery. RESULTS: There were significant improvements both in terms of quality of life and visual function measures in the study group. Benefits were greater in patients with moderate cataract irrespective of the degree of ARMD. No increased incidence in progression to the "wet" form of ARMD was found. Improvements in quality of life measures and visual function were more pronounced in patients with no ocular comorbidities. CONCLUSIONS: Patients with mild and moderate degrees of ARMD do benefit from cataract surgery and the benefits are greater in patients with moderate degrees of lens opacity. Longer follow up is required to assess the risk of increased ARMD progression.

Three dimensional analysis of the lamina cribrosa in glaucoma.

BACKGROUND/AIM: Structural changes in the lamina cribrosa have been implicated in the pathogenesis of glaucomatous optic atrophy. The aim of this study was to determine a measure the surface variability of the cup floor in normal subjects and patients with glaucoma. METHODS: A sample of age matched normal subjects (NN), patients with low tension glaucoma (LTG), and primary open angle glaucoma (POAG) were included in the study. The glaucoma groups were matched for the severity of the visual field loss. Mean 10 degree topographic images of normal and glaucomatous eyes from the Heidelberg retina tomograph were imported into ERDAS image processing software where topographic analysis of the cup floor could be assessed. Each image was processed using customised spatial filters that calculated the surface depth variation in localised neighbourhood areas across each image. The local change in depth across the cup floor surface was determined and compared between the three clinical groups. RESULTS: The depth variation in the cup floor was largest in normal subjects followed by LTG and POAG. Highly statistically significant differences in surface depth variability of the cup floor existed between normal and LTG (p = 0.005), between normal and POAG (p<0.0001), and between LTG and POAG groups (p<0.0001). The variability and skewness of depth difference across the optic cup floor were also significantly different between the three clinical groups. CONCLUSION: A new parameter quantifying depth variations in the cup floor significantly discriminated between groups of normal and glaucoma patients. This new parameter may contribute to a better understanding of the pathogenesis of the glaucomatous optic nerve damage in different types of glaucoma.

Low vision services for vision rehabilitation in the United Kingdom.

AIM: Little is known about the distribution and methods of delivery of low vision services across the United Kingdom. The purpose of this study was to determine the type and location of low vision services within the UK. METHODS: Survey by means of a 29 point postal questionnaire, followed when necessary by a five point telephone questionnaire. All known potential providers of low vision services (n = 2539) including hospitals (n = 277), optician/optometry practices (n = 1683), social services (n = 177), voluntary groups (n = 190), specialist teachers (n = 205), and universities (n = 6) were surveyed. For each service provider, the type, magnitude, and geographical location were determined. The distribution of services across the United Kingdom and the ratio of providers to population density of people with a visual impairment were mapped using the Geographic Information System (GIS). RESULTS: Data were obtained on 1945 (77%) service providers: 1679 (66%) responded to the postal questionnaire and 266 (11%) to the telephone questionnaire. Of all respondents, 59% (n = 1135) offer some form of help to people with a visual disability, of which 26% (n = 497) only sell magnifiers and 33% (n = 638) provide low vision services. It is estimated that in total just under 155,000 low vision consultations are offered annually, the bulk of which are provided by hospital eye departments. The distribution was geographically uneven and there appears to be scarcity in some areas. CONCLUSION: When compared to the probable number of people with a visual impairment in the UK there are apparent inadequacies in service provision in terms of distribution, magnitude, and coordination. The results highlight a need to review current services.

Reflectance pulse oximetry measurements from the retinal fundus.

Conventional transmission pulse oximetry is a noninvasive technique for the continuous monitoring of arterial oxygen saturation (SaO2) from peripheral vascular beds such as the finger tip or earlobe. In this paper we propose to exploit the unique transparency of the ocular media to make reflectance pulse oximetry measurements on the retinal fundus. This technique potentially offers significant advantages over conventional pulse oximetry, primarily the ability to monitor cerebral, as opposed to peripheral, oxygen saturation. We have developed an in vitro system to stimulate the retinal circulation and ocular optics. This system consists of a flexible cuvette located in a model eye and an extracorporeal blood circuit to stimulate arterial blood flow. The system was used to investigate the relationship between SaO2 and the R/IR ratio in reflectance pulse oximetry. To enable in vivo measurements to be made, we also modified a standard haptic contact lens to hold the pulse oximeter probe in front of the pupil. In a preliminary study, the lens was fitted to an awake volunteer and cardiac-synchronous signals were detected by the retinal pulse oximeter.

Cryptococcal pneumonia: a fulminant presentation.

A 32-year-old presented with fulminant, bilateral airspace pneumonia due to Cryptococcus neoformans while under cytotoxic therapy for advanced Hodgkin's disease. We alert physicians to this rapidly progressive form of cryptococcosis which has been poorly described previously and which may closely mimic bacterial pneumonia.

Chemical species in cheese and their origin in milk components.

Cheese making is the process of concentrating milk fat and protein by separation from water and soluble components. The objective of the cheese maker is to maximize yield efficiency by optimum utilization of each milk component while not compromising cheese quality. Cheese yielding potential of milk may be increased by selective breeding for specific protein genotypes, especially the BB variant of both kappa-casein and beta-lactoglobulin. Milk fat is included in cheese by occlusion into the protein coagulum. Participation of casein in both lactic and rennet coagulation is nearly complete so that casein losses to the whey occur mainly during cutting and the early stages of cooking. In lactic cheese, excepting cottage cheese, it is possible to eliminate losses of fines by centrifugal or membrane separation of curd. In heat-acid precipitated varieties protein recovery is increased by inclusion of whey proteins but fat recovery is very dependent on coagulation conditions. In ripened cheese obtaining the correct basic structure and composition is critical to texture and flavour development during curing.

Determination of residues of pirimicarb and its desmethyl and desmethylformamido metabolites in fruits and vegetables by liquid chromatography-electrospray/mass spectrometry.

A method was developed for the simultaneous determination of residues of pirimicarb (I) and its desmethylformamido (II) and desmethyl (III) metabolites in plums, peas, green beans, broad beans, carrots, and swedes. The compounds were extracted with ethyl acetate and determined, without cleanup, by reversed-phase liquid chromatography and electrospray mass spectrometry (MS). MS and MS/MS were used concurrently to monitor the protonated molecules and their common collision-induced dissociation product. The limit of detection (signal-to-noise ratio of >3) was 1 ng/mL, corresponding to crop concentrations of <0.0015 mg/kg. All 3 compounds were determined in plums, broad beans, and green beans by MS without interference. Interferences which affected the determination of desmethylformamido-pirimicarb in peas, and to a lesser extent in carrots and swedes, were eliminated by MS/ MS. Recoveries for all 3 compounds, at 0.05 mg/kg for plums and 0.005 mg/kg for other commodities, were in the range 83-124%. No interconversion of I, II and III, occurred during extraction, and the compounds were stable in extracts for > or = 7 days under appropriate conditions.

A computer-based data acquisition system for breathing and exercise entrainment studies.

An interactive, real-time, computer-based data acquisition system was designed to obtain data for breathing and exercise entrainment studies. By timing the steps of subjects walking on a treadmill relative to different points in the respiratory cycle (e.g. the beginning and end of inspiration), the relation between gait and ventilation can be followed on a breath-by-breath basis. Accurate establishment of the beginning and end of respiratory events from a pneumotachygraph signal was assured by using tidal volume thresholds for (1) noise, (2) minimum valid volume and (3) minimum duration.

Mycobacterial infections in AIDS.

Tuberculosis (TB) remains uniquely important among acquired immune deficiency syndrome (AIDS)-associated opportunistic infections: it presents the greatest public health hazard worldwide, is the most readily curable, and is largely preventable with existing means. Given the expanding pool of human immunodeficiency virus (HIV) seropositive persons, particularly in developing nations where Mycobacterium tuberculosis remains a leading health problem, one can expect a continued rise in TB cases during the 1990s. Global efforts to eliminate TB are now inextricably entwined with the effectiveness of measures to curtail the HIV epidemic. Mycobacterium avium complex infection, currently an intractable late complication of aids, may increase in clinical importance as success in managing other opportunistic infections and HIV disease itself improves. Understanding of the pathogenesis and management of mycobacterial diseases should increase rapidly given the renewed research spurred on by the advent of HIV.