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Biomedical subjects

A Larkin

Publications and source records attributed to A Larkin.

27 records · Page 2Linked to original sources
PubMed1991

Primary structure and processing of the Candida tsukubaensis alpha-glucosidase. Homology with the rabbit intestinal sucrase-isomaltase complex and human lysosomal alpha-glucosidase.

The nucleotide sequence of a 4.39-kb DNA fragment encoding the alpha-glucosidase gene of Candida tsukubaensis is reported. The cloned gene contains a major open reading frame (ORF 1) which encodes the alpha-glucosidase as a single precursor polypeptide of 1070 amino acids with a predicted molecular mass of 119 kDa. N-terminal amino acid sequence analysis of the individual subunits of the purified enzyme, expressed in the recombinant host Saccharomyces cerevisiae, confirmed that the alpha-glucosidase precursor is proteolytically processed by removal of an N-terminal signal peptide to yield the two peptide subunits 1 and 2, of molecular masses 63-65 kDa and 50-52 kDa, respectively. Both subunits are secreted by the heterologous host S. cerevisiae in a glycosylated form. Coincident with its efficient expression in the heterologous host, the C. tsukubaensis alpha-glucosidase gene contains many of the canonical features of highly expressed S. cerevisiae genes. There is considerable sequence similarity between C. tsukubaensis alpha-glucosidase, the rabbit sucrase-isomaltase complex (proSI) and human lysosomal acid alpha-glucosidase. The cloned DNA fragment from C. tsukubaensis contains a second open reading frame (ORF 2) which has the capacity to encode a polypeptide of 170 amino acids. The function and identity of the polypeptide encoded by ORF 2 is not known.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and characterization of a Candida tsukubaensis alpha-glucosidase gene in the yeast Saccharomyces cerevisiae.

The molecular cloning of an alpha-glucosidase gene isolated from a Candida tsukubaensis (CBS 6389) genomic library in Saccharomyces cervisiae is reported. The cloned gene is contained within a 6.2 kb Sau3A DNA fragment and directs the synthesis and secretion of an amylolytic enzyme into the extracellular medium of the recombinant host, S. cerevisiae. The cloned enzyme was found to have an unusually broad substrate specificity and is capable of hydrolysing alpha-1,2, alpha-1,3, alpha-1,4 and alpha-1,6 linked, as well as aryl and alkyl, D-glucosides. On the basis of its substrate specificity profile, the cloned enzyme was classified as an alpha-glucosidase (E.C. 3.2.1.20). It has a pH optimum in the range 4.2-4.6, a temperature optimum of 58 degrees C and is readily inactivated at pasteurization temperature (60 degrees C). Southern blot analysis failed to reveal any homology between the cloned gene and genomic DNA isolated from other well characterized amylolytic yeasts. A rapid plate-assay, based on the utilization of a chromogenic substrate X-alpha-D-glucoside to detect the expression of the cloned alpha-glucosidase in S. cerevisiae transformants, was developed.

Blotting, Southern↗
PubMed1989

Daily life therapy: a Japanese model for educating children with autism.

The controversial practice of Daily Life Therapy, as demonstrated at the Boston Higashi School in Massachusetts, is reviewed. Five fundamental principles of Daily Life Therapy are examined: instruction that is group-oriented; routine activities that are highly structured; instructional techniques that center on learning through imitation; a method for reducing children's levels of unproductive activity through rigorous physical exercise; and a curriculum that focuses on movement, music, and art. These central features of Daily Life Therapy are discussed in light of current theory, research, and educational practices in autism. Empirical questions raised by this unique treatment mode are outlined.

Art↗
PubMed1979

Hyaluronic acid capsule: strategy for oxygen resistance in group A streptococci.

Unencapsulated variants of encapsulated, M-protein-positive group A streptococci are oxygen sensitive and secrete inhibitory concentrations of hydrogen peroxide when grown in aerated broth cultures. The organisms were equally sensitive to hydrogen peroxide, and neither exhibited catalase or peroxidase activity, suggesting that differences in oxygen sensitivity reflect dissimilarity in oxygen uptake. The encapsulated parental culture was found to grow in aggregates that take up oxygen more slowly than unencapsulated, oxygen-sensitive derivatives. Moreover, the latter grow in an unaggregated, homogenous suspension. The enzyme hyaluronidase was able to disrupt aggregates of the encapsulated strain increase the rate that these cells take up oxygen, and cause the accumulation of toxic concentrations of hydrogen peroxide earlier in their growth cycle. The evidence presented shows that the aggregation of streptococcal cells by their hyaluronic acid capsule provides this organism with a novel means to avoid self-destruction by oxygen metabolites--cells are shielded from oxygen. The reduced surface-to-volume ratio and limited diffusion of oxygen into the interior of aggregates are proposed as the protective mechanism.

Aerobiosis↗
PubMedDate not supplied

Fibre mapping--a case study.

Fibre mapping, more commonly known as one-to-one taping, was developed in Germany approximately twenty years ago. The technique facilitates the distribution of fibres on a surface to be recorded. The impact of this technique on the investigation of serious crime has been reported in the European Fibre Group on several occasions. This paper represents a case study of the application of the technique. It is believed to be the first time that this technique has been successfully applied in the United Kingdom.

Journal Article↗
PubMedDate not supplied

Rat ultrasound model for measuring pain resulting from intramuscularly injected antimicrobials.

Rats emit ultrasonic vocalizations in situations involving anxiety or stress, defense, and submission. This study demonstrates the use of ultrasonic vocalizations as a quantitative measure of pain associated with intramuscular (i.m.) injections. Intramuscularly administered cephalosporins used in a comparative evaluation of pain in humans were chosen to validate this rat model. Three groups of four rats each received an intramuscular injection of either drug first, and then placebo, or placebo and then drug. The three drugs used in this study were cefonicid, cefoxitin, and cefamandole; saline was used as the placebo. Ultrasonic vocalizations were measured from 20 kHz to 100 kHz. The number of vocalizations ranged from 50 milliseconds to 500 milliseconds and most of the vocalizations occurred between 60 kHz and 80 kHz. Rats injected with cefoxitin, cefamandole, cefonicid, and saline vocalized an average of 36 +/- 11, 33 +/- 9, 28 +/- 7, and 11 +/- 6 times respectively. The response to all three antimicrobials differed significantly when compared with placebo (p < 0.01), however, there was no significant difference between the number of vocalizations for each antimicrobial injection. Further research may allow the correlation of the total duration of each vocalization, with the individual frequencies such as the 22 kHz and the 55 kHz components and with the amount of pain associated with the injection. This correlation could then be used to further identify differences in the amount of pain associated with each antimicrobial injection without increasing the sample size.

Animals↗
PubMedDate not supplied

Expression and prognostic relevance of Mcl-1 in breast cancer.

BACKGROUND: Bcl-2, an anti-apoptotic protein, is frequently associated with favourable prognosis in breast cancer. The potential role of mcl-1, another bcl-2 family member, in breast cancer has not yet been defined. PATIENTS AND METHODS: This study examined the expression of mcl-1 and bcl-2 in 170 cases of invasive primary breast carcinoma, using reverse-transcriptase polymerase chain reaction and immunohistochemical analyses. RESULTS: Expression of bcl-2 mRNA and protein were found to be favourably associated with outcome for patients, supporting a prognostic role for bcl-2 in breast cancer, whereas mcl-1 expression, at the mRNA or protein level, did not correlate with tumour size, grade, lymph node or ER status, age of patient at diagnosis, or disease outcome. CONCLUSION: As these analyses of mcl-1 expression may have co-detected mcl-1(S/deltaTM) (a more recently identified, shorter variant, that may be pro-apoptotic) with the anti-apoptotic wild-type of mcl-1, it is possible that future studies may indicate some significant clinical correlations if the isoforms can be independently investigated.

Adult↗
PubMedDate not supplied

Effects of specific criteria and calibration on examiner reliability.

The purpose of this pilot study was to investigate the use of specific criteria and examiner calibration on the reliability of inexperienced examiners on dental sealant evaluations. Dental (N = 8) and dental hygiene (N = 8) students participated as examiners. The study objectives were to identify differences in calibrated and non-calibrated examiners, examiners calibrated by an expert or non-expert, and reliability between dental and dental hygiene student examiners. A criterion-referenced evaluation form was used to evaluate dental sealant end product on 20 teeth, twice by each examiner. Eight of 16 examiners participated in a one-hour calibration session between evaluations. The session consisted of a discussion of operational definitions, the evaluation procedure for dental sealants, and use of the criterion-referenced form. Intra- and interexaminer reliabilities were measured. There were no statistically significant differences (p less than .05) in intraexaminer reliability. Although calibration produced no significant increase in interexaminer reliability, the post-training reliability scores for the group calibrated by an expert decreased, and scores for the group calibrated by a non-expert increased. No significant difference was found in reliability between dental and dental hygiene student examiners.

Humans↗