Application of a dry heat treatment to enhance the functionality of low-heat nonfat dry milk.

Nonfat dry milk is a valuable food and ingredient because it contains proteins, fat, carbohydrates, minerals, and vitamins. When manufactured, this product is classified into high heat (HH) or low heat (LH) depending on the pre-heat treatment used in pasteurization. Radio frequency dielectric heating, if used alone or as part of a dry heat technology, may induce component interactions in milk powders, which could alter or improve functionality. To pursue this objective, LH was subjected to radio frequency dielectric heating to 80, 85, and 90°C with a subsequent hold period of 60 or 90 min in an oven, set at the designated temperature, 80, 85, or 90°C, assessed for functionality in liquid and gel systems, cooled, and subsequently compared with LH and HH. The functionality assessment included heat stability and foaming, emulsion, and gelling properties. For foaming, LH presented a statistically lower overrun and foam stability compared with all dry-heated LH. The LH dry-heated at ≥85°C exhibited significantly greater foaming capacity than did the LH. Emulsification properties were not significantly different as a function of dry heating compared with LH. As gels, water-holding capacity was greater and syneresis was significantly less for all gels made with the dry-heated LH at <85°C. Gel firmness and cohesiveness were not affected by dry heating. The heat coagulation time at native pH was significantly greater for LH that were dry-heated for 90 min compared with LH. At adjusted pH (6.4 to 7.2), the heat stability was improved if the LH was dry-heated. The dry-heated LH had significantly less foaming properties, but greater emulsion activity compared with the HH. Overall, the dry heat treatment conditions of this study did not result in acid-induced gels with equivalent properties as gels made with HH. Syneresis was similar for all gels except for those made from the dry-heated LH to 90°C and held for 60 min, as this gel had significantly more syneresis than did the gels made from HH. However, the heat stability of dry-heated LH at native, 6.8, 7.0, and 7.2 pH was greater compared with the heat stability of HH. The application of a dry heat treatment enhanced the functional properties of LH, opening the opportunity to develop food products that can use this modified nonfat dry milk such as ice cream, bakery, and meat products.

Validation of radio-frequency dielectric heating system for destruction of Cronobacter sakazakii and Salmonella species in nonfat dry milk.

Cronobacter sakazakii and Salmonella species have been associated with human illnesses from consumption of contaminated nonfat dry milk (NDM), a key ingredient in powdered infant formula and many other foods. Cronobacter sakazakii and Salmonella spp. can survive the spray-drying process if milk is contaminated after pasteurization, and the dried product can be contaminated from environmental sources. Compared with conventional heating, radio-frequency dielectric heating (RFDH) is a faster and more uniform process for heating low-moisture foods. The objective of this study was to design an RFDH process to achieve target destruction (log reductions) of C. sakazakii and Salmonella spp. The thermal destruction (decimal reduction time; D-value) of C. sakazakii and Salmonella spp. in NDM (high-heat, HH; and low-heat, LH) was determined at 75, 80, 85, or 90 °C using a thermal-death-time (TDT) disk method, and the z-values (the temperature increase required to obtain a decimal reduction of the D-value) were calculated. Time and temperature requirements to achieve specific destruction of the pathogens were calculated from the thermal destruction parameters, and the efficacy of the RFDH process was validated by heating NDM using RFDH to achieve the target temperatures and holding the product in a convection oven for the required period. Linear regression was used to determine the D-values and z-values. The D-values of C. sakazakii in HH- and LH-NDM were 24.86 and 23.0 min at 75 °C, 13.75 and 7.52 min at 80 °C, 8.0 and 6.03 min at 85 °C, and 5.57 and 5.37 min at 90 °C, respectively. The D-values of Salmonella spp. in HH- and LH-NDM were 23.02 and 24.94 min at 75 °C, 10.45 and 12.54 min at 80 °C, 8.63 and 8.68 min at 85 °C, and 5.82 and 4.55 min at 90 °C, respectively. The predicted and observed destruction of C. sakazakii and Salmonella spp. were in agreement, indicating that the behavior of the organisms was similar regardless of the heating system (conventional vs. RFDH). Radio-frequency dielectric heating can be used as a faster and more uniform heating method for NDM to achieve target temperatures for a postprocess lethality treatment of NDM before packaging.

Short communication: radio frequency dielectric heating of nonfat dry milk affects solubility and whey protein nitrogen index.

The US infant formula market is estimated at over $3.5 billion, of which 75% are dairy-based formulas. Dried dairy powders pose a significant food safety risk, with Cronobacter sakazakii and Salmonella spp. being pathogens of particular concern. Radio frequency dielectric heating (RFDH) can provide rapid, uniform heat treatment of dry powders; thus, it potentially may be used as a postprocess lethality treatment for nonfat dry milk (NDM) or powdered infant formula. Because RFDH is a heat treatment, the functionality of the NDM may be altered and should be evaluated. High heat- and low heat-NDM were RFDH processed at temperatures ranging from 75 to 90°C for 5 to 125 min. Products were then assessed for whey protein nitrogen index (WPNI), solubility, and color. In low heat-NDM, RFDH decreased WPNI and solubility if the process was done at ≥ 80°C; however, in high heat-NDM, RFDH had a greater effect on solubility than WPNI and some color properties were altered. Further investigation of RFDH is merited to validate its application as a pathogen control process for NDM across processing parameters that result in acceptable functional properties for infant formula and other food products containing NDM.

To circumcise or not to circumcise? Circumcision in patients with bleeding disorders.

SUMMARY: Circumcision is one of the most common procedures performed in male neonates, but few published reports have described circumcision in patients with bleeding disorders. The aim of this study was to analyse outcomes of circumcision among children evaluated at our institution to determine the extent of complications and to provide guidelines for circumcision management. We searched our patient database for records of children who were followed up at the Mayo Clinic Comprehensive Hemophilia Center from 2000 through 2007 and who had been circumcised. We retrospectively reviewed the medical records to document complications and determine management strategies in this patient population. Of 55 children and young adults identified (median [range] age, 15 years [11 months to 21 years]), 48 patients were circumcised. Indications for circumcision were parental request (n = 45) and medical recommendation (n = 3). Twelve of 21 patients with a known bleeding disorder at the time of circumcision received factor replacement before the procedure. Three of these 21 patients had bleeding complications. Of the other 27 patients, who were diagnosed later in life as having a bleeding disorder, 8 had bleeding complications. The overall incidence of bleeding after circumcision was 23% (11/48). The 23% overall incidence of bleeding complications in our patients with bleeding disorders is comparable to that reported for patients without a bleeding disorder (0.1-35%). Some of our patients had significant bleeding despite adequate factor replacement before and after the procedure. Parents and patients must be aware that bleeding risk is a possibility despite adequate factor replacement for hemostasis.

Central venous access devices for paediatric patients with haemophilia: a single-institution experience.

Use of a central venous access device (CVAD) can facilitate early introduction of home-based infusion of factor concentrate for long-term prophylaxis or immune tolerance therapy in children with bleeding disorders. The aim was to review outcomes associated with use of CVAD. Retrospective review of paediatric patients with bleeding disorders was observed at the Mayo Clinic Comprehensive Hemophilia Center. Thirty-seven CVAD were placed in 18 patients (haemophilia A [n = 15], type 3 von Willebrand disease [n = 2] and haemophilia B [n = 1]). Follow-up was for 45 952 CVAD days, and median time that CVAD remained in place was 1361 days per device. Factor VIII (FVIII) inhibitors were present in 4 of the 15 patients. Ten CVAD-related infections occurred (median, 672 days; range, 72-1941 days), of which six were in one patient with FVIII inhibitors. Overall infection rate was 0.22 (95% confidence interval [CI], 0.10-0.40) per 1000 CVAD days, with 0.11 infections in patients without FVIII inhibitors compared with a pooled incidence of 0.66 (95% CI, 0.44-0.97) reported in the literature. Indications for removal of 27 CVAD were blockage, change to peripheral venous access, catheter displacement, infection, leak in the port septum, short catheter and skin erosion. No clinically apparent thrombosis or sequelae of thrombosis were observed. Infection is the most common complication associated with CVAD use and is increased in patients who have inhibitors. The low rate of clinically apparent thrombosis reflects our practice of not screening for thrombosis. The low infection rate reflects our practice of using and reinforcing the aseptic technique.

Modeling glucose and water dynamics in human skin.

BACKGROUND: Glucose is heterogeneously distributed in the different physiological compartments in the human skin. Therefore, for the development of a noninvasive measurement method, both a good quantification of the different compartments of human skin and an understanding of glucose transport processes are important. METHODS: The composition of human skin was quantified by histology research. Based on this information a mathematical model was developed to simulate glucose dynamics in human skin. RESULTS: The model predicts dynamically glucose concentrations in the different layers of the skin as a result of changes in blood glucose concentration. The model was validated with published time course data of blood and interstitial fluid glucose during a clamp study with three different set points for blood glucose, and model outcomes were compared to measurements for the lag time and gradient. According to the model, glucose in the interstitial fluid of the dermis best matches the amplitude and dynamics of blood glucose. CONCLUSIONS: The new data obtained from quantitative histology appeared crucial for the model. The proposed model was successfully validated. This result was obtained without tuning or fitting of any parameter. It was shown how the model can be used to set standards for measurements and to define the best measurement depth for noninvasive glucose monitoring.

Energy transfer and charge separation in the purple non-sulfur bacterium Roseospirillum parvum.

The antenna reaction centre system of the recently described purple non-sulfur bacterium Roseospirillum parvum strain 930I was studied with various spectroscopic techniques. The bacterium contains bacteriochlorophyll (BChl) a, 20% of which was esterified with tetrahydrogeranylgeraniol. In the near-infrared, the antenna showed absorption bands at 805 and 909 nm (929 nm at 6 K). Fluorescence bands were located at 925 and 954 nm, at 300 and 6 K, respectively. Fluorescence excitation spectra and time resolved picosecond absorbance difference spectroscopy showed a nearly 100% efficient energy transfer from BChl 805 to BChl 909, with a time constant of only 2.6 ps. This and other evidence indicate that both types of BChl belong to a single LH1 complex. Flash induced difference spectra show that the primary electron donor absorbs at 886 nm, i.e. at 285 cm(-1) higher energy than the long wavelength antenna band. Nevertheless, the time constant for trapping in the reaction centre was the same as for almost all other purple bacteria: 55+/-5 ps. The shape as well as the amplitude of the absorbance difference spectrum of the excited antenna indicated exciton interaction and delocalisation of the excited state over the BChl 909 ring, whereas BChl 805 appeared to have a monomeric nature.

Pyruvate dehydrogenase complex deficiency as a cause of subacute necrotizing encephalopathy (Leigh disease).

Leigh disease is a disorder with great clinical variability and for which diverse biochemical causes have been proposed. Clarification requires rigorous correlation of biochemical abnormalities with strict morphologic diagnosis; such an unambiguous association is the subject of this report. A patient with well-documented clinical and biochemical pyruvate dehydrogenase complex deficiency is shown on postmortem examination to have the specific CNS pathology of Leigh disease. These findings, considered together with the aggregate data in the literature, suggest strongly that pyruvate dehydrogenase complex deficiency is the basic defect in a subgroup of patients with Leigh disease.

Central hypoventilation syndrome in pyruvate dehydrogenase complex deficiency.

The presentation and treatment of a central hypoventilation syndrome in a boy with pyruvate dehydrogenase complex (PDHC) deficiency are reported. Dephosphorylated PDHC was assayed in disrupted fibroblasts after pretreatment with dichloroacetate, a pyruvate dehydrogenase kinase inhibitor. Maximal specific activity of activated patient PDHC was 10% to 30% of control values. Patient PDHC activity was not increased by alterations in concentrations of pyruvate or cofactors (thiamine pyrophosphate [TPP], coenzyme A [CoA], oxidized form of nicotinamide adenine dinucleotide [NAD+]). Clinically, normalization of plasma lactate by a high-lipid diet did not prevent slowly progressive neurologic decline. The patient manifested intermittent ataxia, episodic profound weakness, moderate psychomotor retardation, ophthalmoplegia, and retinal pigment epithelial changes. A true central hypoventilation syndrome was documented on the basis of rigorous radiologic, electrophysiologic, and pulmonary function criteria. Theophylline, progesterone, and ritalin neither altered ventilatory response to CO2 nor permitted weaning from the ventilator. In contrast, peripheral chemoreceptor stimulants (intravenous doxapram; oral almitrine) effected an acute doubling of minute ventilation with appropriate decreases in PaCO2. However, a positive response to long-term therapy with almitrine could not be unequivocally shown. It was concluded that measurement of disrupted fibroblast PDHC following dichloroacetate activation constitutes an accurate assay for PDHC deficiency. PDHC deficiency must be considered in the differential diagnosis of the central hypoventilation syndrome; this appears to be the first report of such an association. Finally, a therapeutic trial of a peripheral chemoreceptor agonist is warranted in the management of central hypoventilation syndrome.

Early diagnosis of acute myocardial infarction in patients without ST-segment elevation.

Early identification of acute myocardial infarction (AMI) is necessary to initiate appropriate treatment. In patients presenting without ST-segment elevation, diagnosis is often dependent on the presence of elevated myocardial markers. This study examines the ability of serial MB mass alone and in combination with myoglobin in diagnosing AMI in patients without ST-segment elevation within 3 hours of presentation. In all, 2,093 patients were admitted and underwent serial marker analysis using myoglobin, creatine kinase (CK), and CK-MB at 0, 3, 6, and 8 hours. AMI was diagnosed by a CK-MB > or =8.0 ng/ml and a relative index (RI) (CK-MB x 100/total CK) > or =4.0. A total of 186 patients (9%) were diagnosed with AMI. The optimal diagnostic strategy was an elevated CK-MB + RI on the initial or 3-hour sample or at least a twofold increase in CK-MB without exceeding the upper range of normal over the 3-hour time period (sensitivity 93%, specificity 98%). The combination of an elevated CK-MB + RI or myoglobin on the initial or 3-hour sample had a sensitivity of 94%, although specificity was significantly lower, at 86%. Sensitivities and specificities after exclusion of the 242 patients with ischemic electrocardiographic changes were essentially unchanged. We conclude that most patients with AMI presenting with nondiagnostic electrocardiograms can be diagnosed within 3 hours of presentation.

Experimental infection of Helisoma trivolvis (Colorado strain) snails with cercariae of Echinostoma trivolvis.

A Colorado (CO) strain of Helisoma trivolvis resistant to miracidial infection, but susceptible to Echinostoma trivolvis cercarial penetration, was used to study encystment of cercariae released from naturally infected H.trivolvis (Pennsylvania strain). All 12 snails, 8-10 mm in shell diameter, each exposed to 25 cercariae and necropsied 1-4 days post-exposure were infected with between 9 and 19 cysts per snail (average 14). In all infectivity experiments, regardless of the size (age) of the Colorado strain snails used, encysted metacercariae were recovered from the kidney-pericardial region of experimentally infected snails within 24 h post-exposure. Snails exposed individually with 500 cercariae averaged 230 cysts per snail at 24 h p.i. Cercariae encysted at 6-8 h p.i., but not at 2 and 4 h p.i. Light microscopical observations of the cysts suggested that greater than 99% were viable. Metacercariae subjected to in vitro excystation in an alkaline trypsin-bile salts medium showed excystation rates of 60-85%. In conclusion, H. trivolvis (CO strain) is an excellent experimental second intermediate host for cercarial encystment of E. trivolvis.

Composition and optical properties of reaction centre core complexes from the green sulfur bacteria Prosthecochloris aestuarii and Chlorobium tepidum.

Photosynthetically active reaction centre core (RCC) complexes were isolated from two species of green sulfur bacteria, Prosthecochloris (Ptc.) aestuarii strain 2K and Chlorobium (Chl.) tepidum, using the same isolation procedure. Both complexes contained the main reaction centre protein PscA and the iron-sulfur protein PscB, but were devoid of Fenna-Matthews-Olson (FMO) protein. The Chl. tepidum RCC preparation contained in addition PscC (cytochrome c). In order to allow accurate determination of the pigment content of the RCC complexes, the extinction coefficients of bacteriochlorophyll (BChl) a in several solvents were redetermined with high precision. They varied between 54.8 mM(-1) cm(-1) for methanol and 97.0 mM(-1) cm(-1) for diethylether in the Q(Y) maximum. Both preparations appeared to contain 16 BChls a of which two are probably the 13(2)-epimers, 4 chlorophylls (Chls) a 670 and 2 carotenoids per RCC. The latter were of at least two different types. Quinones were virtually absent. The absorption spectra were similar for the two species, but not identical. Eight bands were present at 6 K in the BChl a Q(Y) region, with positions varying from 777 to 837 nm. The linear dichroism spectra showed that the orientation of the BChl a Q(Y) transitions is roughly parallel to the membrane plane; most nearly parallel were transitions at 800 and 806 nm. For both species, the circular dichroism spectra were dominated by a strong band at 807-809 nm, indicating strong interactions between at least some of the BChls. The absorption, CD and LD spectra of the four Chls a 670 were virtually identical for both RCC complexes, indicating that their binding sites are highly conserved and that they are an essential part of the RCC complexes, possibly as components of the electron transfer chain. Low temperature absorption spectroscopy indicated that typical FMO-RCC complexes of Ptc. aestuarii and Chl. tepidum contain two FMO trimers per reaction centre.

Kinetics of absorbance and anisotropy upon excited state relaxation in the reaction center core complex of a green sulfur bacterium.

Properties of the excited states in reaction center core (RCC) complexes of the green sulfur bacterium Prosthecochloris aestuarii were studied by means of femtosecond time-resolved isotropic and anisotropic absorption difference spectroscopy at 275 K. Selective excitation of the different transitions of the complex resulted in the rapid establishment of a thermal equilibrium. At about 1 ps after excitation, the energy was located at the lowest energy transition, BChl a 835. Time constants varying between 0.26 and 0.46 ps were observed for the energy transfer steps leading to this equilibrium. These transfer steps were also reflected in changes in polarization. Our measurements indicate that downhill energy transfer towards excited BChl a 835 occurs via the energetically higher spectral forms BChl a 809 and BChl a 820. Low values of the anisotropy of about 0.07 were found in the 'two-color' measurements at 820 and 835 nm upon excitation at 800 nm, whereas the 'one-color' kinetics showed much higher anisotropies. Charge separation occurred with a time constant varying between 20 and 30 ps.

Effect of ACTH-(4-10) on equilibrium compensation after unilateral labyrinthectomy in the squirrel monkey.

Daily injection of ACTH-(4-10) was given to squirrel monkeys for a 28 day period to modify the characteristics of the post-unilateral labyrinthectomy symptoms along the course of the equilibrium compensation. When compared to the results of the control group, the ACTH-(4-10) injection groups (daily dose 250 micrograms/kg or 500 micrograms/kg) showed a significant improvement of acquisition and maintenance of compensation both in the spinal locomotor balance function and the oculomotor balance function.

Infestation of Peromyscus leucopus and Tamias striatus by Ixodes scapularis (Acari: Ixodidae) in relation to the abundance of hosts and parasites.

The risk of humans acquiring Lyme disease is a function of the local density of nymphal and adult ticks that are infected with Lyme disease spirochetes. This in turn, will be related to host-use patterns of ticks and to the densities of both juvenile ticks and their hosts. At a forested site in Dutchess County, NY, we quantified host-use patterns of larval and nymphal Ixodes scapularis Say infesting the 2 dominant vertebrate hosts, white-footed mice and eastern chipmunks, during a 3-yr period. Larval tick burdens were 2-3 times higher on mice than they were on chipmunks, whereas nymphal tick burdens were > 3 times higher on chipmunks than they were on mice. We used multiple regression analysis to examine juvenile tick and host densities as independent variables influencing tick burdens. The density of questing larval ticks was positively correlated with larval tick burdens on mice, whereas the density of questing nymphs was weakly related to nymphal burdens on either host. Effects of the densities of mice and chipmunks on tick burdens were strong in some years, but weak in others. Moreover, the sign of the regression coefficients changed from one year to the next. We argue that these results are inconsistent with a passive encounter model of host selection, and suggest instead that either tick behavior or host responses cause strong biases in the distribution of juvenile ticks on their hosts.

Neurologic complications in galactosemia.

Two siblings, a 27-year-old man and his 24-year-old sister were diagnosed with classic transferase deficiency galactosemia at birth and were treated with strict lactose restriction. Despite well-documented dietary management, both siblings are mentally retarded and manifest a progressive neurologic condition characterized by hypotonia, hyperreflexia, dysarthria, ataxia, and a postural and kinetic tremor. Magnetic resonance imaging revealed moderate cortical atrophy, a complete lack of normal myelination, and multifocal areas of increased signal in the periventricular white matter on T2-weighting. These patients suggest that even with early diagnosis and treatment, individuals with galactosemia may have significant neurologic morbidity with abnormalities of white matter development. This finding raises the possibility of biochemical heterogeneity within the classic transferase deficiency group, as well as the possibility of a lack of available galactose metabolites necessary for glycolipid synthesis causing a disruption of normal myelin development.

Characterization of beta-conglycinin and glycinin soy protein fractions from four selected soybean genotypes.

The beta-conglycinin and glycinin fractions of soy protein were isolated from Macon, Ohio FG1, Enrei, and IL2 genotypes that were grown under the same environmental conditions. The soy protein fractions were evaluated to determine whether chemical composition and gel-forming properties were related. Amino acid analyses suggested that the hydrophobic residues may be the primary cause of differences in soy protein gel characteristics as the storage moduli increased with higher percentages of hydrophobic residues. Reversed-phase high-performance liquid chromatography profiles revealed variations in the composition of each fraction that corresponded to differences observed among the storage moduli. The gel-forming properties may be related to more than just protein content, such as the amount and type of amino acid in the fraction.

Time and temperature of stretching as critical control points for Listeria monocytogenes during production of mozzarella cheese.

Different heating times and temperatures commonly used during curd stretching were investigated to determine their effects on the viability of Listeria monocytogenes in mozzarella cheese. Pasteurized whole milk was inoculated with two levels of L. monocytogenes (7 and 3 log CFU/g) and coagulated with citric acid and rennet. The curd was stretched at 55, 66, and 77 degrees C for 1, 3, and 5 min. Results indicated that the majority of L. monocytogenes cells remained in the cheese curds at both inoculum levels. Stretching at 66 degrees C for 3 min reduced the number of L. monocytogenes by 5 log units, whereas stretching at 55 degrees C had a minimal effect. Stretching at 77 degrees C resulted in the complete demise of L. monocytogenes cells (from 7.6 log CFU/g to < 1.0 log CFU/g) in 1 min. If the stretching temperature partially reduced microbial counts, bring (4 degrees C for 12 h) usually had a lethal effect on the remaining microorganisms, but was less effective than the stretching temperature. These results show that stretching curd at 66 degrees C for 5 min or 77 degrees C for 1 min can effectively control L. monocytogenes during the production of mozzarella cheese.

Emergence of cercariae of Echinostoma trivolvis from Helisoma trivolvis under different conditions.

Release of Echinostoma trivolvis cercariae from naturally infected Helisoma trivolvis snails maintained under different laboratory conditions was studied. Infected snails were isolated for 1 hr in Stender dishes containing 5 ml of artificial spring water and the number of cercariae released during this time was recorded. Of the conditions tested, i.e., light versus dark, day versus night, volume of water, snail maintenance temperature prior to isolation, temperature during isolation, food versus no food, aeration of water, disturbance of water, and isolation in snail conditioned water, the only significant factors in the emergence of E. trivolvis cercariae were temperature related. Observations on cercariae released in vitro from isolated rediae maintained in Locke's solutions were in accord with the in vivo results.