Diurnal variation in trunk kinematics during a typical work shift.

Diurnal variation in trunk flexibility, defined as changes in range of motion, has been previously observed and quantified. Prior studies have shown that decreased disk height occurs as the day progresses and allows the spinal ligaments to slacken, resulting in an increase in the range of motion (flexibility) and a possible reduction in the risk of injury. This risk may be accentuated under dynamic motions of the spine. This study was conducted to observe the change in dynamic trunk mobility as a function of time of the day. Trunk motions of 21 men were observed at three specific times of the day using a triaxial electrogoniometer. No variation in trunk range of motion in any of the cardinal planes was observed. However, velocity and acceleration in the sagittal plane showed significant variations, suggesting the reexamination of the "slack ligaments" hypothesis. This study asserts that identifying flexibility by only its static component, range of motion, gives only partial information about the diurnal variation experienced by the spine. Industrial injuries occurring in the early morning hours may be a result of insufficient trunk mobility. This study indicates that risk associated with diurnal variation is far more complex than originally thought.

Acid secretion from a Meckel's diverticulum: the unsuspected mimic of Crohn's disease?

The commonest causes of ulceration in the terminal ileum are Crohn's disease, infection, and neoplasia. Meckel's diverticulum is said to be found more commonly in patients with Crohn's disease than in the general population. We describe a patient who developed extensive terminal ileal ulceration caused by acid secretion from gastric mucosa within a Meckel's diverticulum, a condition that has not been recognized before. Our patient demonstrated a number of clinical features that would be consistent with Crohn's disease, and we wonder whether the rare condition of "Meckel's ileitis" is occasionally misdiagnosed as Crohn's disease in other patients.

Angiographic cystoid macular edema after posterior chamber lens implantation.

We performed a prospective study evaluating the incidence of angiographic cystoid macular edema (CME) following extracapsular cataract extraction and posterior chamber intraocular lens implantation. Of the 162 eyes in the study, 141 were randomized into either a primary capsulotomy or a capsule intact group. The remaining eyes were not randomized due to intraoperative surgical complications, but they were included in the follow-up studies. Six weeks after surgery, angiographic CME was documented in 24% of the capsulotomy group and in 16% of the capsule intact group. The differences were not statistically significant. Including nonrandomized cases reduced the overall incidence of angiographic CME and the difference between the two groups. Angiographic CME was usually not extensive, and it was associated with a visual acuity less than 20/40 in 2.5% of eyes six weeks postoperatively. A subgroup of 120 eyes was followed up for approximately six months, when angiographic CME was present in 4% of the capsulotomy and capsule intact groups.

Hepatic sinusoidal endothelium in goats.

The ultrastructure of the hepatic sinusoids of the goat was examined. Contrary to current belief concerning this and other ruminant species, we found the sinusoids to be lined by a smooth, continuous layer of endothelium, broken only by the presence of numerous, unoccluded fenestrae which provide a direct path of communication between the sinusoidal lumen and the space of Disse. Therefore, we suggest that a sieving function similar to that which has been shown to occur in rats may be attributed to the sinusoidal endothelium of the goat.

Hepatic sinusoidal endothelium in sheep: an ultrastructural reinvestigation.

Following perfusion fixation of livers from fetal, neonatal, and adult sheep, the ultrastructure of the fenestrated sinusoidal endothelium was examined. In contrast to an earlier report which utilized immersion fixation, we found the fenestrae to be unoccluded by diaphragms or basal lamina, thus offering only a discontinuous barrier between the blood and the space of Disse and hepatocytes. This observation was confirmed by perfusing the liver with marker particles. The fenestrae appear, therefore, to have a sieving function, regulating the metabolism of particulate matter such as lipoproteins in sheep in a similar manner to that which has been shown to occur in rats.

Small liver fenestrae may explain the susceptibility of rabbits to atherosclerosis.

Rabbits fed cholesterol rapidly develop high serum cholesterol levels which lead to the development of atherosclerosis. This is related to the retention of cholesterol-rich chylomicron remnants in the circulation. In most animals, such as rats, chylomicron remnants are rapidly removed from the circulation by the liver. The first barrier to this removal is the fenestrated endothelium of liver sinusoids. Measurements made of a large number of sinusoidal fenestrae by scanning electron microscopy have shown the average diameters to be 89 nm in rats and 49 nm in rabbits. We postulate that the small size of endothelial fenestrae in the liver sinusoids of rabbits hinders the egress of chylomicron remnants from the sinusoidal blood, explaining the subsequent development of hypercholesterolemia and atherosclerosis.

Test procedures to evaluate effects of chemical exposure on fertility and reproduction.

Various methods have been developed to assess the effects of chemical substances on reproduction. In some instances, the tests have been developed to define the effects of treatment on specific segments of the reproductive cycle. In other cases, studies are conducted to determine the cumulative effects of treatment during one or more generations. The structure, advantages, and disadvantages of three types of conventional reproduction studies are reviewed. An outline of the procedural sequences, observations, and record evaluation required in the three-period reproduction study, the three-generation reproduction study, and the multigeneration reproduction study are presented.

Toxicity of combustion products from burning polymers: development and evaluation of methods.

Laboratory and room-scale experiments were conducted with natural and synthetic polymers: cotton, paper, wood, wool, acetate, acrylic, nylon, and urethane. Smoke and off-gases from single materials were generated in a dual-compartment 110-liter exposure chamber. Multicomponent, composite fuel loads were burned within a 100 m(3) facility subdivided into rooms. In chamber experiments, mortality depended on the amount of material burned, i.e., fuel consumption (FC). Conventional dose (FC)/mortality curves were obtained, and the amount of fuel required to produce 50% mortality (FC(50)) was calculated. With simple flame ignition, cotton was the only material that produced smoke concentrations lethal to rats; FC(50) values for cotton ranged from 2 g to 9 g, depending on the configuration of the cotton sample burned. When supplemental conductive heat was added to flame ignition, the following FC(50) values were obtained; nylon, 7 g; acrylic, 8 g; newsprint, 9 g; cotton, 10 g; and wood, 11 g. Mortality resulting from any given material depended upon the specific conditions employed for its thermal decomposition. Toxicity of off-gasses from pyrolysis of phosphorus-containing trimethylol propane-polyurethane foams was markedly decreased by addition of a flame ignition source. Further studies are needed to determine the possible relevance of single-material laboratory scale smoke toxicity experiments. Room-scale burns were conducted to assess the relative contributions of single materials to toxicity of smoke produced by a multicomponent self-perpetuating fire. Preliminary results suggest that this approach permits a realistic evaluation of the contribution of single materials to the toxicity of smoke from residential fires.

Ischaemic necrosis of the gallbladder following hepatic artery embolism.

A case of ischaemic necrosis of the gallbladder due to hepatic artery embolism diagnosed at operation and treated successfully by cholecystectomy and embolectomy is presented. The clinical and biochemical features are described, together with a short review of the literature.

An evaluation of the L-methionine activity of the hydroxy analogue of methionine.

Three product forms of methionine hydroxy analogue were prepared for biological evaluation of their L-methionine activity for broiler strain chickens (Vantress x Arbor Acres). Two samples of the acid of the analogue HA-50, LMA-70 and one sample of a commercial grade (90%) MHA were standarized by gas liquid chromatography to contain a known amount of L-methionine activity as the free analogue acid. Each product form was tested in a separate experiment. The experimental chickens were fed a practical corn-soybean meal basal diet for the first seven days of the test. A semi-purified diet composed primarily of cerelose, isolated soybean protein and soybean meal was used for the remainder of the experimental period. HA-50 and the commercial form of the hydroxy analogue were formulated to contain 50% L-methionine activity. Hence, they were added to the diets at 0.1 and 0.2% and compared to the L-methionine standard which was added to levels of 0.05, 0.1 and 0.15%. LMA-70 was formulated to contain 70% L-methionine activity and was added to the experimental diets at 0.07 and 0.14% and compared to the L-methionine standard at the same levels used in the other experiments. Statistical analysis of four-week data revealed no difference between the biological response of L-methionine and the three forms of the analogue when tested at comparable L-methionine activity levels. The biological of the analogue products was in good agreement with the L-methionine activity determined by gas liquid chromatography.