Effect of marginal zinc deficiency on the lymphatic absorption of [14C]cholesterol

The effect of zinc deficiency on intestinal absorption of cholesterol was investigated in adult male rats fed 3.6 ppm of dietary zinc (ZD) and compared with pair-fed (PF) and ad-libitum (CT) controls fed 30.6 ppm of zinc for 10 to 12 wk. The intestinal absorption of cholesterol was measured by collecting the mesenteric lymph at hourly intervals for 8 h after infusing a dose of [14C]cholesterol in a lipid emulsion through an indwelling duodenal catheter. Data on the hourly lymphatic output of [14C]cholesterol showed that the absorption of [14C]cholesterol plateaued at 4 h postdosing in all groups. The rate of the appearance of [14C]cholesterol in the mesenteric lymph significantly decreased in ZD rats at 5 h and thereafter. The cumulative absorption of [14C]cholesterol by ZD rats for the 8-h period was 4.4 +/- 1.0% of the dose, compared with 11.8 +/- 1.1% by PF and 10.7 +/- 1.4% by CT rats. There were no differences in percent distribution of esterified [14C]cholesterol among the three groups. Also, no significant change in mucosal cholesterol esterase activity was observed due to zinc deficiency. The present data and previous findings taken together suggest that the primary mechanism responsible for the impaired absorption of cholesterol may be associated with defective formation of chylomicrons in the intestinal mucosa.     

Aluminum contamination of infant formulas

This study aims to determine the extent of aluminum (Al) contamination in whole milk, milk formulas, and other nutrient products commonly used for infants. Similar products from different manufacturers and different lots were measured for Al using electrothermal atomic absorption technique. Aluminum measurements were made directly from the samples or after reconstitution or dilution with Al-free water. Aluminum content was lowest (less than 50 micrograms/liter) in human milk, whole cow milk, and products that appear to require minimal manufacture processing and have few additives such as skim milk, cow milk with 2% fat, bottled glucose water, and sterile water. Highest Al levels (up to 2346 micrograms/liter) were found in highly processed and modified formulas including soy formula, preterm infant formula, and formulas for specific metabolic disorders. Aluminum content of humanized cow milk formula and bottled glucose-electrolyte solution were between the two ranges and usually less than 400 micrograms/liter. There were no significant differences in Al content of similar products from different manufacturers. Liquid formula stored in glass bottles has highest Al content compared to that stored in steel cans or powder preparation of the same product (p less than 0.05). Thus there are marked differences in Al loading depending on the type of formula, whether it is a powder or liquid preparation and the type of storage container. We speculate that raw materials such as soybean, additives such as calcium and phosphorus, manufacturing processes and storage containers are potential sources of contamination of infant formulas.     

Ischemic necrosis of the entire femoral head and rapidly destructive hip disease: potential causative relationship

 Objective. Rapidly destructive hip disease (RDHD) is an uncommon disorder of the hip that has been considered a disease of unknown cause and distinct from ischemic necrosis of the femoral head. The objective of this study was to investigate ischemic necrosis of the femoral head as one potential cause of RDHD. Design and patients. In 600 patients who underwent MR imaging of the hip, 20 cases of ischemic necrosis involving the entire femoral head in 18 patients (3%) were retrospectively studied with routine radiography and MR imaging. All patients had surgically confirmed ischemic necrosis of the femoral head. Results and conclusions. All patients showed rapid destruction of the femoral head on routine radiography and MR imaging as compared with the gradual onset of clinical symptoms. Plain radiographs showed several bone fragments at the inferomedial aspect of the femoral head (75%), acetabular erosions (55%), eccentric depression at the lateral articular surface of the femoral head conforming to the adjacent acetabulum (35%), and mild osteoarthritis (15%). Bone sclerosis was often present at sites of impaction between the femoral head and the acetabulum. MR imaging showed marked distention of the joint capsule in all cases. In 14 of 20 cases, the contents of the joint space showed predominantly low or intermediate signal intensity on T1- and T2-weighted images. Ischemic necrosis involving the entire femoral head may represent one of the causes of RDHD.     

Staphylococcal toxins: screening of burn wound isolates and evidence for alphahaemolysin production in the burn wound

Culture filtrates of Staphylococcus aureus strains isolated from burn patients were examined for cytotoxic activities. A large molecular weight cytotoxin (MW=253000 daltons) that exhibited cytotoxicity for human foreskin cells and haemolytic activity against human and rabbit erythrocytes was identified. The cytotoxic activity could be completely neutralized by antiserum formed against the cytotoxin. Further characterization of the molecule by isoelectric focusing revealed that the cytotoxin was composed of at least two toxic factors of smaller molecular weight. Both factors exhibited cytotoxicity to tissue-culture cells. however, one factor lysed rabbit but not human erythrocytes whereas the other factor had the opposite haemolytic pattern. The cytotoxicity of each factor was neutralized by the antiserum formed against the cytotoxin. A cytotoxic factor that exhibited haemolytic activity for rabbit erythrocytes, and that was neutralized by the cytotoxin antiserum, was identified in burn wound extracts of mice infected with Staph. aureus. On the basis of molecular weight and isoelectric focusing data, we conclude that the large molecular weight cytotoxin was composed of an aggregation of alpha-haemolysin and another presently unidentified toxic molecule, possibly delta-toxin. Alpha-haemolysin appears to be produced in vivo during experimental staphylococcal burn wound infection.     

Angiostrongylus (Parastrongylus) eosinophilic meningitis

Angiostrongylus (Parastrongylus) cantonensis is the commonest cause of eosinophilic meningitis in the world. Infective third-stage larvae develop in slugs and snails. Humans are infected primarily in the central nervous system after ingesting an infected intermediate host. Damage by motile worms, inflammatory responses to foreign bodies, and possible toxicity of worm substances work in concert to produce the pathologic and clinical picture of neurologic angiostrongyliasis. This disease manifests itself by headache, paresthesias, generalized weakness, and occasionally visual disturbances and extraocular muscular paralysis. Eosinophilic pleocytosis is the major laboratory finding. Although the diagnosis of neurologic angiostrongyliasis is usually made clinically, serologic methods such as ELISA (enzyme-linked immunosorbent assay) can be helpful. Occasionally, living larvae can be identified histologically in the CSF, eye, or other tissue. There is no specific treatment for this disease. Corticosteroids may be useful to relieve increased intracranial pressure. The role of anthelmintic drugs, such as thiabendazole and ivermectin, is not yet known. The prognosis of neurologic angiostrongyliasis is usually good; however, fatal and chronic cases do occur. Appropriate preparation of food, control of mollusks and planarians, and elimination of rodents are important measures in limiting the further spread of eosinophilic meningitis caused by A. cantonensis.     

Dietary habits and lung cancer risk among Chinese females in Hong Kong who never smoked

This describes a retrospective study in which 88 lung cancer patients and 137 district-matched controls were interviewed concerning the effects of diet on lung cancer risk among Hong Kong Chinese women who never smoked tobacco. Those in the lowest tertile of consuming fresh fruit or fresh fish had statistically significant adjusted relative risks (RRs) of 2.4 and 2.8, respectively. The protective effects of diet, i.e., higher consumption of leafy green vegetables, carrots, tofu, fresh fruit, and fresh fish, were confined mostly to those with adenocarcinoma or large cell tumors. Only fresh fruit was found to positively, and smoked meats to negatively, affect the risk of squamous or small cell tumors. Foods high in vitamin C, retinol, and calcium seemed to exert larger effects. Subjects from larger households were shown to be more frequent consumers of fresh vegetables, fruit, and fish. Because the lifetime weighted household size could be used as a surrogate index of past dietary quality, when it was combined with current dietary intakes of fresh fruit, the RR increased as either factor decreased in a dose-response manner. The adjusted RR was 5.8 at the lowest level. Further testing of the validity of the lifetime weighted household size as an index of past dietary quality is needed.