Gas-Liquid chromatography of fatty derivatives. I. Separation of homologous series ofa-olefins,n-hydrocarbons,n-nitriles,and n-alcohols

Summary Gas-liquid chromatography has been shown to be applicable to the analysis of several fatty derivatives. The difficulties inherent in conventional separation schemes such as liquid-liquid chromatography, fractional distillation, and crystallization can be overcome through the use of gas-liquid chromatography. It becomes the preferred procedure for several reasons: a) fractions are more nearly pure, b) analysis time is a fraction of the time required for conventional separations, c) operational procedures are simple and highly reproducible, d) sample size requirements are low, e) the cost per unit analysis is low. These factors suggest that gas-liquid chromatography is highly useful as an analytical tool in fat research. In many cases the determination of chainlength distribution has already become a routine function. There remain areas in which gas-liquid chromatography has not been completely successful. Until very recently the separation of fatty methyl esters of similar chain length and varying degrees of unsaturation has been time-consuming and tedious. Several new partitioning agents hold out great promise in the separation of the isomeric C₁₈ fatty acids. More selective partitioning agents and refined techniques undoubtedly will equally improve the resolution of unsaturated alcohols and other unsaturated fatty derivatives. Presented at annual meeting, American Oil Chemists' Society, Memphis, Tenn., April 21–23, 1958. Technical Paper No. 160, Archer-Daniels-Midland Company.     

Sr对Mg-1.7Si合金中初生和共晶Mg_2Si相的变质作用

为了获得性能优良的耐热镁合金,研究了Sr对初生和共晶Mg_2Si相的变质作用,并利用扫描电子显微镜观察了Mg_2Si相的形貌特征与Mg-1.7Si-x Sr合金的微观组织.结果表明,当Sr的质量分数处于1.0%~1.5%范围内时,可对初生和共晶Mg_2Si相进行有效变质.Sr的吸附作用可以诱发孪晶沟槽、旋转晶界等原子扩展台阶的出现,引起原子堆砌方式和晶体生长方向的改变,因而Sr可对初生Mg_2Si相起到变质作用.Sr的添加还可将Mg+Mg_2Si共晶的长大方式由合作长大模式变为以重新形核为主兼有合作长大的混合模式,使得Mg_2Si相的生长形态产生改变,因而Sr可对共晶Mg_2Si起到变质作用.     

Cross-Campus Collaboration to Produce Camtasia-Enhanced Lessons to Improve Distance Learning

This pilot study examines the use of Camtasia-enhanced lessons to supplement distance education provided to medical laboratory science students. More programs of study are available as distance learning opportunities, creating challenges to find better ways to present material. Librarians provided technical expertise necessary to produce a Camtasia video. This helped instructors prepare engaging lectures for phlebotomy to supplement the PowerPoint presentations and self-directed lessons provided in previous courses. Medical laboratory science faculty collaborated with library staff to produce videos that demonstrate proper phlebotomy technique using training personnel and faculty, whom the students eventually interact with in the clinical environment.     

Loss of heterozygosity and overexpression of the p53 gene in ovarian carcinoma

Eight anticonvulsant drugs-including clonazepam, diazepam and phenobarbital-were tested for their effects on GABA-stimulated chloride uptake in rat cerebral cortical microsacs (unfiltered synaptoneurosomes). "Mid" and "high" therapeutic concentrations were screened, and, if significant enhancement was found, full concentration-response tests were done. In the initial screens, enhancement of GABA-stimulated uptake was found only with phenobarbital, clonazepam and diazepam. In subsequent concentration-response tests, the effects of phenobarbital were found to occur throughout the range of normal, anticonvulsant concentrations, whereas the effects of clonazepam and diazepam were observed only above the concentrations normally used for the chronic control of seizures or anxiety. These data suggest that phenobarbital's anticonvulsant effects are mediated via the GABAA receptor complex, but that the low-dose effects of the benzodiazepines may be mediated via some other mechanism.     

Subjects presented at ASHP Midyear Clinical Meetings, 1967-90

The subject matter and trends of presentations made at ASHP Midyear Clinical Meetings (MCMs) were studied. A computerized database of information from MCM and Annual Meeting (AM) program and abstract books was created. The data were analyzed to determine the distribution of MCM presentations by subject and by author for the period 1967 to 1990, determine if there were differences in subjects covered between MCMs and AMs, explore the proposition that there has been duplication of material in MCM presentations, and evaluate the frequency with which MCM presentations have been published in ASHP journals. The total number of presentations made at MCMs from 1967 through 1990 was 8180, while the total for the AMs was 1547 for the two periods (1962-71 and 1985-90) studied. The most common keywords in titles were "pharmacy," "drug," "patient," "hospital," and "service." All International Pharmaceutical Abstracts subject categories and two other categories were represented; presentations in the institutional pharmacy practice category were the most frequent, while pharmacognosy-related presentations were least frequent. The overwhelming number of authors made only one presentation and were listed as the first author. The subjects of presentations were similar between AMs and MCMs. A tendency toward duplication of material was found. Of the 8180 MCM presentations, at least 1005 were published in an ASHP journal. Between 1967 and 1990, presentations at MCMs covered a wide range of subjects but were sometimes duplicative or not on the cutting edge.     

Cytomechanics of axonal development

Mechanical tension is a robust regulator of axonal development of cultured neurons. We review work from our laboratory, using calibrated glass needles to measure or apply tension to chick sensory neurons, chick forebrain neurons, and rat PC12 cells. We survey direct evidence for two different regimes of tension effects on neurons, a fluid-like growth regime, and a nongrowth, elastic regime. Above a minimum tension threshold, we observe growth effects of tension regulating four phases of axonal development: 1. Initiation of process outgrowth from the cell body; 2. Growth cone-mediated elongation of the axon; 3. Elongation of the axon after synaptogenesis, which normally accommodates the skeletal growth of vertebrates; and 4. Axonal elimination by retraction. Significantly, the quantitative relationship between the force and the growth response is surprisingly similar to the simple relationship characteristic of Newtonian fluid mechanical elements: elongation rate is directly proportional to tension (above the threshold), and this robust linear relationship extends from physiological growth rates to far-above-physiological rates. Thus, tension apparently integrates the complex biochemistry of axonal elongation, including cytoskeletal and membrane dynamics, to produce a simple "force input/growth output" relationship. In addition to this fluid-like growth response, peripheral neurons show elastic behaviors at low tensions (below the threshold tension for growth), as do most cell types. Thus, neurites could exert small static forces without diminution for long periods. In addition, axons of peripheral neurons can actively generate modest tensions, presumably similar to muscle contraction, at tensions near zero. The elastic and force-generating capability of neural axons has recently been proposed to play a major role in the morphogenesis of the brain.     

Designing Personalized Garments with Body Movement

The standardized sizes used in the garment industry do not cover the range of individual differences in body shape for most people, leading to ill-fitting clothes, high return rates and overproduction. Recent research efforts in both industry and academia, therefore, focus on virtual try-on and on-demand fabrication of individually fitting garments. We propose an interactive design tool for creating custom-fit garments based on 3D body scans of the intended wearer. Our method explicitly incorporates transitions between various body poses to ensure a better fit and freedom of movement. The core of our method focuses on tools to create a 3D garment shape directly on an avatar without an underlying sewing pattern, and on the adjustment of that garment's rest shape while interpolating and moving through the different input poses. We alternate between cloth simulation and rest shape adjustment based on stretch to achieve the final shape of the garment. At any step in the real-time process, we allow for interactive changes to the garment. Once the garment shape is finalized for production, established techniques can be used to parameterize it into a 2D sewing pattern or transform it into a knitting pattern.     

Expression, characterization, and detection of human uridine phosphorylase and identification of variant uridine phosphorolytic activity in selected human tumors

Uridine phosphorylase (UPase) catalyzes the reversible phosphorolysis of uridine to uracil. We purified the enzyme from the murine colon 26 tumor using a two-step procedure through 5-amino-benzylacyclouridine affinity chromatography. Antibodies raised in rabbits against the purified protein revealed single bands in Western blots of normal human tissue and tumor extracts. The polyclonal antibody used to screen a human liver expression library allowed the isolation of a 1.2-kb clone that contained the entire open reading frame of the human UPase. The UPase cDNA has been expressed as a fusion protein in Escherichia coli using the pMal-C2 vector. The kinetic analysis demonstrated that the recombinant UPase preferentially uses uridine, 5-fluorouracil, and uracil as substrates, although lower levels of activity were observed with 2-deoxyuridine and thymidine. Clinical samples of human tumors and adjacent normal tissues were assayed for phosphorolytic activity and sensitivity to 5-benzylacyclouridine (BAU), a potent inhibitor of the enzyme presently in Phase I-II clinical trial. Activity in normal tissues appeared to be low but very sensitive to BAU (approximately 90% inhibition at 10 microM). Tumors had generally 2-3-fold greater activity compared with adjacent normal tissues. In breast cancer specimens and head-neck squamous carcinomas, however, uridine cleavage was only partially inhibited (40-60%) by 10 or 100 microM BAU. The BAU-insensitive activity requires phosphate and pH conditions similar to the normal enzyme, and the new phosphorolytic activity was independent from thymidine phosphorylase. The BAU-insensitive phosphorolytic activity in selected tumors, coupled with the potent inhibitory activity of BAU against the "classical" uridine phosphorylase in normal human tissues, provides the rationale for combining BAU with 5-fluorouracil in the treatment of breast and head-neck tumors.     

Clinicopathologic analysis of microscopically invasive breast carcinoma

Breast biopsy or mastectomy cases having diagnoses of carcinoma in situ with "microinvasion," "minimal invasion," "focal invasion," or "suggestive of invasion" were reviewed and all histologically identified foci of invasive disease from each case were measured using an ocular micrometer. Cases in which any single focus of invasion was greater than 5 mm or the added size of separate invasive foci exceeded 10 mm were excluded, resulting in a study group of 75 patients. Invasive neoplasm was present in the initial biopsy in 69 of 75 cases (92%); however, residual invasive neoplasm was found in the subsequent lumpectomy/mastectomy from 14 of these (20%). In 59% of cases, two or more histologically separate foci of invasion were identified. Invasive foci consisted of isolated cells or cell clusters, each less than 1 mm (microfocal invasion), in 33% of cases. In 12 cases, the sum of individual invasive foci was 5 to 10 mm. Axillary lymph nodes (LN) from 5 of 69 patients (7%) contained metastatic carcinoma (four cases, one LN positive; one case, two LN positive). The cumulative sizes of all invasive foci in the LN-positive group were microfocal invasion (one case), 0.6 mm (one case), 1.1 mm, 2.5 mm, and 5.8 mm. The difference in frequency of axillary node metastasis between tumors with microfocal and measurable invasion (4.3% v 8.6%) was not statistically significant. Follow-up data were available on 55 cases (mean interval, 66.1 months). One (node-negative) patient had duct carcinoma in situ recurrence in the same breast 4 years after initial treatment. Another (with unknown node status) developed an axillary lymph node metastasis 13 months after initial treatment (96% disease-free survival). We conclude that microscopic stromal invasion in breast carcinoma, at least in the setting of significant in situ component, is often initiated from multiple foci. Patients with microscopically invasive breast carcinoma have a small but significant risk of axillary metastases, although a highly favorable survival.     

Proline isomerization-independent accumulation of an early intermediate and heterogeneity of the folding pathways of a mixed alpha/beta protein, Escherichia coli thioredoxin

Oxidized Escherichia coli thioredoxin (Trx) is a small protein of 108 residues with one disulfide bond (C32-C35 essentially involved in the activity) and no prosthetic moieties, which folds into a structural motif containing a central twisted beta-sheet flanked by helices that is found in many larger proteins. The kinetics of refolding of Trx in vitro have been investigated using a newly developed active site titration assay and continuous or stopped-flow (SF) methods in conjunction with circular dichroism (CD) and fluorescence (Fl) spectroscopy. These studies revealed the presence of early folding intermediates with "molten globule or pre-molten globule" characteristics. Measurements of the ellipticity at 222 nm indicated that about 68% of the total change associated with refolding occurred during the dead time (4 ms) of the stopped-flow instrument, suggesting the formation of substantial secondary structure. The reconstruction of the far-UV CD spectrum of the burst intermediate using combined continuous and stopped-flow methods showed the formation of a defined secondary structure that contains more beta-structure than the native state. Kinetic measurements using SF far-UV CD and Fl over a wide range (0.087-6 M) of GuHCl concentrations at two temperatures (6 and 20 degreesC) demonstrated that the population formed during the 4 ms dead time contained multiple species that are stabilized mainly by hydrophobic interactions and undergo further folding along alternative pathways. One of these species leads directly and rapidly to the native state as demonstrated by active site titration, while the two others fold into a fourth intermediate that is slowly converted to the native protein. Double-jump experiments suggest that the heterogeneity in folding behavior results from proline isomerizations occurring in the unfolded state. Conversely, the accumulation of the burst intermediate does not depend on proline isomerizations.