Disposition of D-[U-14C]tagatose in the rat.

The purpose of this experiment was to determine the disposition of D-tagatose, under development as a low-calorie sweetener, in conventional and germ-free male rats. One group of conventional rats was fed a diet containing D-tagatose (100 g/kg) mixed with the nonpurified diet (900 g/kg) for 28 days. Then, [U-14C]-labeled D-tagatose was administered as a single dose (approximately 220-380 kBq) to 4 of these adapted rats, as well as to 15 conventional and germ-free rats with no prior exposure (i.e., unadapted) to D-tagatose. Eleven of the 19 dosed animals (4 adapted conventional, 3 unadapted conventional and 2 unadapted germ-free, all dosed orally, plus 2 unadapted conventional dosed intravenously) were placed in metabolism chambers and samples of CO2, urine, and feces taken at regular intervals. At termination, a complete material balance was obtained based on the recovery of 14C. Over the 6-h digestive period, D-tagatose was metabolized to release 39.9 and 13.9% of the oral dose as CO2 in the adapted conventional rats and in the unadapted germ-free rats, respectively. Total releases approximated 68 and 22%, respectively. The difference in CO2 evolution is ascribed to microbial fermentation of D-tagatose in the gut of the conventional rats. The role of adaptation was confirmed by finding 93% less D-tagatose in the feces of the adapted conventional rat than in the feces of the unadapted conventional rat. The intestinal absorption of D-tagatose in the rat is estimated to be 20%. The results demonstrate that D-tagatose is metabolized primarily by microorganisms in the gut of the rat, with an upper limit between 15 and 20% of oral dose metabolized by the host.

Effects of acute and repeated oral doses of D-tagatose on plasma uric acid in normal and diabetic humans.

D-tagatose, a stereoisomer of D-fructose, is a naturally occurring ketohexose proposed for use as a low-calorie bulk sweetener. Ingested D-tagatose appears to be poorly absorbed. The absorbed portion is metabolized in the liver by a pathway similar to that of D-fructose. The main purpose of this study was to determine if acute or repeated oral doses of D-tagatose would cause elevations in plasma uric acid (as is seen with fructose) in normal humans and Type 2 diabetics. In addition, effects of subchronic D-tagatose ingestion on fasting plasma phosphorus, magnesium, lipids, and glucose homeostasis were studied. Eight normal subjects and eight subjects with Type 2 diabetes participated in this two-phase study. Each group was comprised of four males and four females. In the first phase, all subjects were given separate 75 g 3-h oral glucose and D-tagatose tolerance tests. Uric acid, phosphorus, and magnesium were determined in blood samples collected from each subject at 0, 30, 60, 120, and 180 min after dose. In the 8-week phase of the study, the normals were randomly placed into two groups which received 75 g of either D-tagatose or sucrose (25 g with each meal) daily for 8 weeks. The diabetics were randomized into two groups which received either 75 g D-tagatose or no supplements of sugar daily for 8 weeks. Uric acid, phosphorus, magnesium, lipids, glycosylated hemoglobin, glucose, and insulin were determined in fasting blood plasma of all subjects at baseline (time zero) and biweekly over the 8 weeks. The 8-week test did not demonstrate an increase in fasting plasma uric acid in response to the daily intake of D-tagatose. However, a transient increase of plasma uric acid levels was observed after single doses of 75 g of D-tagatose in the tolerance test. Plasma uric acid levels were found to rise and peak at 60 min after such dosing. No clinical relevance was attributed to this treatment-related effect because excursions of plasma uric acid levels above the normal range were small and were of short duration. Consistent with earlier observations on fructose, the increase of plasma uric acid was associated with a slight decrease of plasma phosphorus and a slight increase of magnesium. The daily ingestion of D-tagatose for 8 weeks had no effect on fasting plasma magnesium, phosphorus, cholesterol, triglycerides, glycosylated hemoglobin, glucose, and insulin levels. The ingestion of three 25-g doses per day for a period of 8 weeks resulted in varying amounts of flatulence in seven of the eight subjects, and some degree of diarrhea in six subjects. D-tagatose holds promise as a sweetener with no adverse clinical effects observed in these studies.

Sugar substitutes: their energy values, bulk characteristics, and potential health benefits.

Restriction of dietary energy extends life and reduces incidences of disease in animals. These benefits would likely extend to humans. However, diet restriction in animals imposes reductions of 30-50% in food intake, which is probably unacceptable to humans. Low-energy sweeteners used in beverages offer minor reductions in energy intake. However, they lack the bulk required for baked goods and other sugar-rich foods. Full-bulk sweeteners providing about one-half the energy of sugar are under development for such uses. Laxation limits their acceptable dose. Even within such limitations, they can help achieve the health benefits for humans indicated by diet restriction. D-Tagatose, a new candidate sweetener, is nearly as sweet as sucrose and has the bulk of sucrose, yet provides zero available energy. We discuss its potential contribution to human diet restriction along with its specific effect in delaying the aging effects of glycosylation.

The disaccharide effect of sucrose feeding on excretion of intravenously injected [1,2-3H]aldosterone and conjugated glucuronic acid in normotensive rats.

The hypothesis tested was that feeding rats sucrose rather than invert sugar (50:50 mixture of glucose and fructose) or cornstarch would result in a more rapid excretion of glucuronides and tritium from intravenously injected [1,2-3H]aldosterone. Thirty 56-d-old male rats of the Sprague-Dawley strain were fed for 8 wk one of three diets containing 45% of dietary energy from sucrose, invert sugar or cornstarch; 15% of energy was from protein and 40% from fat. Body weights and systolic blood pressures were measured weekly. After 60 d of feeding the diets ad libitum, all rats were injected intravenously with [1,2-3H]aldosterone and the percent recovery of tritium in both urine and feces was determined over the next 4 d. Urinary and fecal excretion of both free and conjugated glucuronic acid was determined over those 4 d. Urinary excretion of sodium and potassium (mg/d) was also determined. There were no differences between groups in food or water intakes, body weights, systolic blood pressures, daily fecal weights and daily urine volumes. The cornstarch-fed group excreted less sodium and potassium than did the other groups (P less than 0.05). The sucrose-fed group had a greater 4-d excretion of tritium (urinary + fecal) than did the invert sugar- or cornstarch-fed groups (P less than 0.01). The sucrose-fed group had a greater percentage of excreted glucuronic acid that was conjugated (urinary + fecal) than did the invert sugar- or cornstarch-fed groups (P less than 0.05). These results tended to confirm the hypothesis.

Effect of mercuric ion on attraction to light of artemia sp nauplii.

Living organisms exhibit a phototactic response which can be altered by certain environmental toxic chemical species. The analysis of photobehavior can help in elucidating environmental factors that influence photomotility reactions of the organisms. A method has been developed that measures the phototactic response of Artemia nauplii under the influence of mercuric ion (Hg2+) in synthetic seawater. The phototactic response of Artemia nauplii was manifested by movement of the organisms from a darkened half to lighted half of an experimental vessel containing synthetic seawater. The density as a function of time of Artemia nauplii is determined by removing aliquots from both light and dark sides and then plating on agar for counting under the dissecting microscope. Measurements consistently show a significant movement of nauplii to the lighted side within 45 min of the start of the experiments. The present investigation demonstrated that at concentrations as low as 0.010 mg HgCl2/liter there is an enhancement of phototactic effect on Artemia nauplii by mercuric ion as compared with control. The phototactic response of Artema nauplii is altered by mercuric ion in a dose-related manner, but the mechanism of this effect is presently unknown.

Inhibition of adenosine triphosphatase in vitro by silver nitrate and silver sulfadiazine.

Inhibition of adenosine triphosphatase (ATPase) by silver nitrate (AgNO3) in vitro was studied in microsomal fractions or tissue homogenates of canine brain and kidney, and human kidney. In microsomal fractions, AgNO3 was an indiscriminate inhibitor of ouabain-sensitive (Na+ + K+ ATPase) and ouabain-insensitive (Mg2+ ATPase) activities with 50% inhibition obtaining at concentrations on the order of 10(-7) to 10(-6)M. The enzyme was protected by cysteine. Changing the concentrations of Na+, K+, H+, Mg2+ and ATP did not alter the fractional inhibition of Na+ + K+ ATPase by a constant concentration of AgNO3. An aqueous suspension of silver sulfadiazine had an inhibitory potency similar to AgNO3. It was concluded that silver gives a different pattern of Na+ + K+ ATPase inhibition than other metallic inhibitors of the enzyme so far examined.

Febrile illness in Malaysia--an analysis of 1,629 hospitalized patients.

We studied 1,629 febrile patients from a rural area of Malaysia, and made a laboratory diagnosis in 1,025 (62.9%) cases. Scrub typhus was the most frequent diagnosis (19.3% of all illnesses) followed by typhoid and paratyphoid (7.4%); flavivirus infection (7.0%); leptospirosis (6.8%); and malaria (6.2%). The hospital mortality was very low (0.5% of all febrile patients). The high prevalence of scrub typhus in oil palm laborers (46.8% of all febrile illnesses in that group) was confirmed. In rural Malaysia, therapy with chloramphenicol or a tetracycline would be appropriate for undiagnosed patients in whom malaria has been excluded. Failure to respond to tetracycline within 48 hours would usually suggest a diagnosis of typhoid, and indicate the need for a change in therapy.

Doxycycline propylaxis for human scrub typhus.

The use of doxycycline, as a prophylactic antibiotic against scrub typhus was investigated in a prospective, randomized, double-blind study. Twenty volunteers were divided into two similar groups. Beginning three days before exposure to Leptotrombidium fletcheri chiggers infected with Rickettsia tsutsugamushi, and continuing for six weeks after exposure, one group received weekly 200-mg oral doses of doxycycline and the other group received a placebo. Nine of 10 doxycycline-treated subjects remained well during prophylaxis but developed antibody to scrub typhus, whereas nine of 10 subjects given the placebo required treatment for scrub typhus. Therefore, the efficacy of the regimen in preventing scrub typhus was 89% (eight cases prevented of nine expected). Ten days after successfully completing prophylaxis, eight of nine subjects reported minor self-limiting symptoms. A single dose of doxycycline was given on day 3 of illness to volunteers who developed scrub typhus. Such therapy was initially effective but was frequently followed by relapse and cannot be recommended.

Transmission of scrub typhus to human volunteers by laboratory-reared chiggers.

Laboratory-reared, Rickettsia tsutsugamushi-infected Leptotrombidium arenicola and L. fletcheri chiggers were fed on 1 and 2 human volunteers respectively. All subjects developed typical clinical signs and symptoms of scrub typhus beginning days 8-10 post chigger attachment (PCA); these included fever, severe headache, myalgia, regional lymphadenopathy, and eschar. The two L. fletcheri subjects developed a transient generalized rash on days 3-4 after the onset of fever, and these two individuals also appeared to suffer a more severe clinical disease. Rickettsemias were detected in all three volunteers beginning on day 7 PCA, 1-3 days before the onset of clinical disease. Rises in indirect fluorescent antibody titers occurred starting on days 13-19 PCA (day 4-11 post fever) and in Weil-Felix OXK titers starting on days 26-22 PCA (days 7-14 post fever). These results strongly suggest that the use of laboratory-reared chiggers is a reliable means of transmitting scrub typhus infections to volunteers.

The longevity of antibody to Rickettsia tsutsugamushi in patients with confirmed scrub typhus.

Serological surveillance for up to two years of 114 patients with laboratory confirmed scrub typhus showed that antibody to Rickettsia tsutsugamushi as demonstrated by the indirect fluorescent antibody test is short-lived. The mean reversion time from mean peak titre (1:499) was 48.9 weeks and the calculated annual reversion rate to a titre less than 1:50 was 61%. This can be used to estimate attack rates based on point prevalence of antibody. The relationship between antibody prevalence and attack rates observed by other workers was confirmed using this model. The possible uses of the finding and its implications in Malaysia are briefly discussed.

Inhibition by vanadium of sodium and potassium dependent adenosinetriphosphatase derived from animal and human tissues.

Inhibition of adenosinetriphosphatase (ATPase) by vanadium pentoxide (dissolved in water or in sodium hydroxide solution) was studied in microsomal fractions and tissue homogenates of kidney, brain, and heart of several species, including humans (kidney only). In some preparations vanadium was found to be the most potent inhibitor of Na+ + K+ATPase activity so far reported. Concentrations of vanadium causing 50 percent inhibition of Na+ + K+ATPase activity ranged from 6 x 10(-8) to 5 x 10(-7) M in microsomal fractions and from 2 x 10(-7) to 1 x 10(-6) M in tissue homogenates. Renal and cardiac enzymes were more sensitive to vanadium than the brain enzyme, a phenomenon independent of enzyme specific activity. The enzyme in tissue homogenates was more resistant to vanadium than the microsomal enzyme derived from the same tissues, suggesting a presence in tissues of protective agents. Mg2+ ATPase, which contaminated the enzyme preparations to a variable degree, was 1,000-10,000 times more resistant to vanadium than was Na+ + K+ATPase. More detailed studies on the mechanism of inhibition were performed with dog and human kidney enzymes. The reversible nature of the inhibition was suggested by the fact that fractional inactivation of Na+ + K+ATPase by vanadium was independent of enzyme protein concentrations. The inhibitory effect was reduced by Na+ and increased by K+ or Mg2+. ATP alone, but not MgATP, antagonized the inhibition. This could mean that vanadium inhibits the Na+ + K+ATPase at the site activated by Na+, and that ATP protects the enzyme either by binding vanadium or by competing for a mutual receptor on the enzyme. The inhibition was reduced by bovine serum albumin, probably binding vanadium. The inhibition was also diminished by reducing agents, ascorbic acid and citric acid.

Single dose doxycycline therapy for scrub typhus.

A single dose of 200 mg of doxycycline was shown to be as effective as a seven day course of tetracycline, in patients suspected of having scrub typhus. 65 (44%) of the 149 patients studied fulfilled the criteria for definite diagnosis of scrub typhus; 10 had an additional diagnosis. Rickettsia tsutsugamushi was isolated from 49 (75%) patients. There was no difference between the two treatment groups in time to defervescence, abolition of cough and headache, or in the time taken to recover well-being. There were no relapses in either group. Of the remaining 84 patients, a causal diagnosis was achieved in 52. Irrespective of a diagnosis there was no difference in apparent response to either doxycycline or tetracycline.

Inhibitory characteristics of lead chloride in sodium- and potassium- dependent adenosinetriphosphatase preparations derived from kidney, brain, and heart of several species.

Inhibition of adenosinetriphosphatase (ATPase) by lead chloride (PbCl2) was studied in microsomal fractions or tissue homogenates of kidney, brain, and heart of several species, including humans. The concentration of PbCl2 causing 50% inhibition (I50) of Na+ + K+ ATPase activity varied from 8 X 10(-6) to 8 X 10(-5) M, depending on the species and organ of origin of the enzyme. The enzyme preparations derived from various parts of the kidney showed no differential sensitivity to PbCl2. These differences in sensitivity to lead were not related to specific activity of the enzyme or to the protein content of the preparations studied. Mg2+ ATPase, which contaminated the enzyme preparations to a variable degree, was 10--100 times more resistant to PbCl2 than was Na+ + K+-activated ATPase. The following more detailed studies were performed on the dog brain and/or kidney enzyme. The inhibition of microsomal Na+ + K+ ATPase was characterized by reversible kinetics. The inhibitory effect was antagonized by Na+, increased by Mg2+, and not altered by K+. ATP alone, or together with Mg2+, antagonized the inhibition. Disodium edetate prevented or reversed the inhibition. These inhibitory characteristics suggest that Pb2+ inhibits Na+ + K+ ATPase at the Na+-dependent phosphorylation site, and that ATP chelates Pb2+ in competition with Mg2+. Combining Pb2+ with ATP may not only result in a reduction of ATPase activity but also cause a relative ATP deficiency if lead is present in sufficiently high concentration.

The life history of a colony of Leptotrombidium (Leptotrombidium) fletcheri (Womersley & Heaslip) infected with Rickettsia tsutsugamushi.

The life cycle of 5 generations of Leptotrombidium (L.) fletcheri infected with Rickettsia tsutsugamushi and reared under ambient temperatures in Malaysia was presented and compared with a colony reared at a constant 27 degrees C (Neal and Barnett, 1961). In general our colony had a longer generation time (average of 54 days from engorged larvae to adult compared with 37 days) and produced fewer eggs (average of 127.9 compared with 900.0) than the comparison colony. Possible factors causing these differences are discussed.