Essential role of a kinesin-like protein in Arabidopsis trichome morphogenesis

Little is known about how cell shape is controlled. We are using the morphogenesis of trichomes (plant hairs) on the plant Arabidopsis thaliana as a model to study how cell shape is controlled. Wild-type Arabidopsis trichomes are large, single epidermal cells with a stalk and three or four branches, whereas in zwichel (zwi) mutants the trichomes have a shortened stalk and only two branches. To further understand the role of the ZWI gene in trichome morphogenesis we have cloned the wild-type ZWICHEL (ZWI) gene by T-DNA tagging, and report here that it encodes a member of the kinesin superfamily of microtubule motor proteins. Kinesin proteins transport diverse cellular materials in a directional manner along microtubules. Kinesin-like proteins are characterized by a highly conserved “head” region that comprises the motor domain, and a nonconserved “tail” region that is thought to participate in recognition and binding of the appropriate cargo.     

Cholecystokinin-stimulated peak lipase concentration in duodenal drainage fluid: a new pancreatic function test

OBJECTIVE: Hormonal stimulation with secretin or cholecystokinin (CCK) is the most sensitive means of assessing pancreatic function. Secretin is not available, and current CCK tests are cumbersome, requiring dual tube intubation and marker perfusion techniques. The aim of this study was to test the efficacy of a new CCK-stimulated pancreatic function test measuring peak lipase concentration. METHODS: A Dreiling gastroduodenal tube was inserted to the ligament of Treitz, and fluid was collected on ice for 80 min in four 20-min aliquots. CCK was infused i.v. at a constant rate of 40 ng/kg/h. Gastric aspirations were discarded. Duodenal aspirates were analyzed for volume and enzyme concentration with a clinical laboratory autoanalyzer. RESULTS: Nineteen healthy volunteers and 18 chronic pancreatitis patients were studied. Lipase concentration and secretory volume showed a peak response by 40 min of stimulation, whereas amylase response was variable. The mean peak lipase concentrations (+/-SEM) for normal volunteers and mild, moderate, and advanced chronic pancreatitis patients were 16.9+/-1.9, 7.9+/-1.7, 3.7+/-1.2, and 2.1+/-0.6 x 10 5 IU/L, respectively. Lower peak lipase concentrations were significantly associated with more advanced chronic pancreatitis (p < 0.001). The receiver operating characteristic curve area for all chronic pancreatitis patients was 0.944 (95% CI = 0.825-0.985). A peak lipase concentration of 780,000 IU/L provided a sensitivity and specificity of 0.833 and 0.867, respectively. This CCK test was well tolerated and without complications. CONCLUSIONS: Lipase concentration in duodenal fluid increases nearly 3-fold from baseline after CCK stimulation in healthy volunteers but is markedly reduced in patients with chronic pancreatic disease. Peak lipase concentration is a significant predictor of chronic pancreatitis and correlates with severity of pancreatic disease. Aspiration of duodenal drainage fluid with a Dreiling tube and analysis with a laboratory autoanalyzer are less cumbersome than marker perfusion and back titration techniques. Measurement of enzyme concentration instead of output could lead to the development of an endoscopic or through-the-scope screening method for assessing patients with suspected chronic pancreatitis or chronic abdominal pain.     

Accuracy and safety of dry needle placement in the piriformis muscle in cadavers

Objectives: The purpose of this anatomic investigation is to (1) establish accuracy of dry needle placement into the medial third of the piriformis muscle as it exits the pelvis from the greater sciatic notch in unembalmed cadaveric specimens, while avoiding puncture of the sciatic nerve, and (2) establish guidelines for dry needle length selection.

Methods: Dry needles were placed in nineteen unembalmed cadaveric posterior hips. Dissection of the posterior hip musculature was performed to confirm location of the needle. A binary decision (yes/no) was made to determine whether the needle reached the piriformis muscle, went through the piriformis muscle, and/or pierced the sciatic nerve. Additionally, mean adipose tissue thickness, gluteus maximus muscle thickness, and perpendicular distance from the needle to the exiting sciatic nerve were recorded.

Results: The needle reached the medial third of the piriformis in 16 out of 19 hips (84.2% accuracy) and never punctured the sciatic nerve. There was a fair (r = 0.493) and good (r = 0.759) correlation between the needle length and the mean fat thickness for the left and right hips, respectively.

Discussion: A physical therapist was able to use bony landmark palpation to locate the piriformis muscle and use estimated adipose tissue thickness to choose a sufficient needle length to reach the medial third of the piriformis muscle. While the needle placement technique was safe and no sciatic nerve puncture occurred, the proximity of the piriformis muscle to the sciatic nerve warrants caution during needle placement.

Level of Evidence: 2c     

Do patients have a voice? The social stratification of health center governing boards

Context

To ensure community responsiveness, federally qualified health centres (FQHCs) in the United States are required to be governed by a patient majority. However, to the extent that these patient trustees resemble the typical low‐income patients served by FQHCs, status generalization theory suggests that they will be passed over for leadership positions within the board in favour of more prestigious individuals.

Methods

Using 4 years of data on health centre governing boards obtained from the Health Resources and Services Administration via a Freedom of Information Act Request, the likelihood of holding executive committee office is modelled as a function of trustee characteristics using Chamberlain''s conditional logistic regressions.

Results

The results indicate that representative patient trustees are significantly less likely than other trustees to hold a position on the executive committee or serve as board chair.

Conclusions

Given the power of the board leadership to set the agenda, the reduced likelihood of representative patient trustees serving in leadership positions may ultimately limit the representative voice given to patients, making FQHCs potentially less responsive to their communities. These findings also have important implications for other settings where engaging and empowering patients is sought.     

The Liver in Acquired Immune Deficiency Syndrome: Emphasis on Patients with Intravenous Drug Abuse

To assess the spectrum of hepatic abnormalities in acquired immune deficiency syndrome (AIDS), we reviewed clinical, biochemical, and pathological material in 32 patients with AIDS. Eight-four percent of AIDS cases had a history of intravenous drug abuse. Ninety percent of AIDS patients has some liver biochemical abnormality at the first presentation of illness. During the course of AIDS, significant (p less than 0.05, paired Student's t test) rises in alkaline phosphatase and bilirubin occurred, without rises in aminotransferases. Mean abnormalities were mild, reflecting approximately 2-fold increases over baseline. Liver failure was not believed to contribute to the death of any AIDS patient. Pathological findings in AIDS included specific infectious diagnosis in 26%, granulomas in 16%, hemosiderosis in 26%, nonspecific abnormalities in 39%, cirrhosis in 23%, and chronic active hepatitis in 3%. AIDS cases were also compared to 10 selected age, sex, and epidemiologically similar non-AIDS patients. Although granulomas or infections were not seen in our comparison group, only the incidence of chronic active hepatitis was significantly different between the groups. If only those with intravenous drug abuse were studied, then none of 24 AIDS patients versus four of eight non-AIDS cases (p less than 0.005) had chronic active hepatitis. AIDS patients with specific hepatic infections tended to have a higher alkaline phosphatase and aspartate aminotransferase (p less than 0.05) than noninfected cases. However, substantial overlap existed, and no difference in hepatomegaly was noted. Ninety percent of AIDS patients were ingesting at least one potentially hepatotoxic drug. We conclude that AIDS patients have a high incidence of underlying hepatic abnormalities. However, clinical and biochemical abnormalities are similar in our selected liver biopsy patients with intravenous drug abuse with or without AIDS. As expected, AIDS patients have a higher incidence of hepatic granulomas and infections, but these patients were not clearly distinguishable from other AIDS cases. Histological examination showed a wide array of changes by light microscopy, but no specific lesion of AIDS was noted. The low incidence of chronic active hepatitis in this AIDS population may imply that the altered T lymphocyte function in AIDS could influence the course of liver disease in these patients.     

Immunoreactive luteinizing hormone, follicle stimulating hormone and their subunits in tissue culture media from normal and adenomatous, human pituitary fragments

Fragments from 4 human pituitaries removed at surgery from one gonadectomized man and three women (one with Nelson's syndrome, one with Forbes Albright syndrome and one with chromophobe adenoma) were grown in tissue culture. The tissue culture medium was changed at weekly intervals, pooled and applied to a Sephadex G-100 column for gel filtration. In each eluate luteinizing hormone (LH), follicle stimulating hormone (FSH), alpha subunit and the beta subunits of LH and FSH were measured by specific radioimmunoassays. For comparison the pituitary standard LER 907 was similarly studied. LH and FSH were measurable in all studies. LH eluted over a broad area whereas FSH eluted as a much sharper peak. In all culture media and in LER 907 large quantities of alpha subunit were detected. The beta subunits of LH and FSH were not present in the LER 907 standard. LHbeta subunit was present in the culture medium of the pituitary fragments from the castrated man and from the women with Nelson's syndrome and Forbes Albright syndrome but not in that of the woman with chromophobe adenoma. FSHbeta subunit was detectable only in the latter case.