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Biomedical subjects

L Cooper

Publications and source records attributed to L Cooper.

At least 73 records · Page 4Linked to original sources
PubMed1993

On the biosynthesis of bovine pancreatic trypsin inhibitor (BPTI). Structure, processing, folding and disulphide bond formation of the precursor in vitro and in microsomes.

The natural gene for bovine pancreatic trypsin inhibitor (BPTI) was expressed by in vitro transcription/translation systems as the 100-residue pre-proBPTI, with a signal peptide for translocation into the endoplasmic reticulum. Expression in the presence of microsomes defined the site of co-translational cleavage of the signal peptide. The resulting proBPTI in the microsomes consists of the 58 residues of mature BPTI, plus an additional 13 residues at the N terminus, including a cysteine residue at position -10, and seven residues at the C terminus. ProBPTI remained in the unfolded, reduced form within microsomes when synthesized under reducing conditions, but folded and formed disulphide bonds rapidly when the disulphide form of glutathione was added. Complete folding could occur within about one minute, even when residue Cys10 was replaced by Ser. The structure of proBPTI was determined by circular dichroism and two-dimensional NMR and found to be that of mature BPTI with flexible extensions on both termini. Its inhibition of the activity of alpha-chymotrypsin was indistinguishable from that of the mature protein. The extensions of the precursor appeared to play only very minor roles in refolding in vitro under conditions where folding and disulphide bond formation are coupled. Under pH and redox conditions thought to reflect those in vivo, complete folding and disulphide bond formation required several hours. Addition of protein disulphide isomerase to in vitro folding experiments caused substantial and similar increases in the rate of formation of the fully folded state for both mature BPTI and proBPTI; the half time for folding to the native state was reduced to approximately two minutes, which is comparable to that occurring in microsomes. The absence of substantial effects of the N and C-terminal extensions on the protein structure, inhibitor activity and refolding leaves their functional roles to be discovered.

Amino Acid Sequence↗
PubMed1993

Behavioral problems among twins.

Despite the frequency of multiple births, little information is available to assist parents and health professionals in the identification and management of behavior problems in multiple-birth siblings. Three case reports are presented that describe quarreling, aggression, and feeding problems among twins. To develop intervention strategies most appropriate for the problem behavior, it is important to determine whether (1) parents are able to effectively implement the intervention strategy, (2) behavior is isolated to one sibling, and (3) different reasons are responsible for similar behavior in siblings. Structured observations were used to determine whether the undesired behavior occurred to escape nonpreferred activities, gain access to preferred activities, or obtain parental attention. The cases provide a framework to facilitate the identification and management of common behavior problems occurring among multiple-birth siblings.

Child Behavior Disorders↗
PubMed1992

Comparison of diazepam with progestin for effectiveness in suppression of urine spraying behavior in cats.

The most common treatment for urine spraying and marking in cats has been administration of long-acting progestins. Treatment with diazepam has recently been gaining favor, particularly because of reported adverse effects of progestins. Results of a clinical trial involving 20 cats indicated that diazepam was effective in eliminating or markedly reducing spraying in 11 (55%) of them. However, most cats required continuous treatment, or at least intermittent treatment, when spraying recurred. The physiologic and behavioral dependency of cats on diazepam, which presumably develops over the course of administration, may contribute to the tendency for spraying to recur once diazepam treatment is discontinued. Using data from previously published findings on progestin administration, plus additional cases, it was documented that a significantly (P less than 0.05) higher percentage of males than females responded favorably. Although the number of cases was not sufficient for a statistical comparison of diazepam vs progestin treatment with regard to male vs female, possible gender difference in the effectiveness of diazepam was not indicated.

Animals↗
PubMed1992

Cloning and sequencing of the cDNA encoding the human homologue of the murine immunoglobulin-associated protein B29.

Membrane-bound immunoglobulins (Ig) on the surface of murine B cells are noncovalently associated with a heterodimeric protein complex of MB-1 and B29 (also called Ig-alpha and Ig-beta). The Ig-associated proteins are predicted to regulate the assembly and transport of the Ig complex to the cell surface and to couple membrane-bound Ig to intracellular signal transduction pathways. We have isolated and sequenced a full-length cDNA clone encoding the human homologue of the B29 protein. The predicted amino acid sequence was compared to its murine counterpart, to MB-1 and to the human T cell receptor (TcR)-associated CD3 proteins. The alignment of the human B29 protein with its murine counterpart revealed 90% homology in the C-terminal portion comprising the cytoplasmic tails, the transmembrane regions and the adjacent 26 amino acids of the extracellular regions. Only 59% homology was found in the rest of the Ig-like extracellular domains. The high degree of conservation observed for the C-terminal amino acids suggested that these domains of the proteins play important functional roles for the Ig complex. Indicative of this was the conservation of the antigen receptor tail motif D-(X)7-E/D-(X)2-Y-(X)2-L-(X)7-Y-(X)2-L/I which is thought to be a component of signal transduction pathways. This motif is also found in the human and murine MB-1 proteins as well as in the TcR-associated CD3 molecules. Further regions of homology between B29, MB-1 and the CD3 proteins included extracellular residues which were predicted to maintain the Ig-like structure, and hydrophilic residues within the transmembrane regions which may be utilized during the intracellular assembly and transport of the oligomeric Ig/MB-1/B29 or TcR/CD3 complexes. Thus the similarities found between B29, MB-1 and the CD3 proteins suggest conserved functions for both the Ig- and TcR-associated proteins.

Amino Acid Sequence↗
PubMed1991

The Anopheles punctulatus complex: DNA probes for identifying the Australian species using isotopic, chromogenic, and chemiluminescence detection systems.

Isotopic and enzyme-labeled species-specific DNA probes were made for the three known members of the Anopheles punctulatus complex of mosquitoes in Australia (Anopheles farauti Nos. 1, 2, and 3). Species-specific probes were selected by screening total genomic libraries made from the DNA of individual species with 32P-labeled DNA of homologous and heterologous mosquito species. The 32P-labeled probes for A. farauti Nos. 1 and 2 can detect less than 0.2 ng of DNA while the 32P-labeled probe for A. farauti No. 3 has a sensitivity of 1.25 ng of DNA. Probes were then enzyme labeled for chromogenic and chemiluminescence detection and compared to isotopic detection using 32P-labeled probes. Sequences of the probe repeat regions are presented. Species identifications can be made from dot blots or squashes of freshly killed mosquitoes or mosquitoes stored frozen, dried, and held at room temperature or fixed in isopropanol or ethanol with isotopic, chromogenic, or chemiluminescence detection systems. The use of nonisotopic detection systems will enable laboratories with minimal facilities to identify important regional vectors.

Alkaline Phosphatase↗
PubMed1991

Adult discharge planning and nursing home placement: a study of risk factors for quality assurance.

OBJECTIVE: A study of two large groups of patients was conducted in a large general hospital, comparing the admission characteristics of those referred to nursing homes and those returning home, to identify factors on admission that would facilitate more rapid discharge planning and placement. METHOD: Discharge planning at the Royal Brisbane Hospital was analysed over 12 months, comparing the admission characteristics of 191 patients placed in nursing homes with 444 patients returning home. RESULTS: Referral of patients to social workers was delayed and poorly co-ordinated, leading to prolongation of the discharge process or placement for nursing home patients. The data indicate that the process can be expedited by attention to readily recognizable factors already present on admission.

Activities of Daily Living↗
PubMed1990

A component analysis of functional communication training across three topographies of severe behavior problems.

We evaluated the separate treatment components of a functional communication training program for 3 severely handicapped persons who each displayed different topographies of aberrant behavior. Following a functional analysis of maintaining conditions for inappropriate behavior (self-injury, stereotypy, aggression), each participant was trained to emit a communicative response that functioned to solicit reinforcement. For 2 participants, consequences (time-out or graduated guidance) for inappropriate behavior were also included. Treatment continued until the participants emitted the communicative response independently and no occurrences of inappropriate behavior were observed for at least two sessions. Following treatment, the separate contributions of the treatment components for communicative responding and for inappropriate behavior were evaluated with a reversal design. The results indicated that both sets of treatment components were necessary for maximal control over aberrant behavior. These results are discussed in relation to the efficiency, history, and control over reinforcement of both appropriate and inappropriate responses.

Behavior Therapy↗
PubMed1989

Use of an intraaortic balloon pump as a pneumatic ventricular assist device controller.

Using a circulatory analogue, we investigated sequentially the performance of a dedicated ventricular assist device driver and an intraaortic balloon pump when driving a pneumatic ventricular assist device. Each drive device was compared under identical pumping conditions at rates of 40 to 120 cycles/min against two resistances. Our preliminary study showed that a modified intraaortic balloon pump could drive a pneumatic ventricular assist device as effectively as its dedicated driver. The necessary modifications to and possible further development of the intraaortic balloon in this role are discussed.

Assisted Circulation↗
PubMed1987

Successful use of a right ventricular assist device.

Right ventricular failure caused by myocardial infarction may be refractory to treatment designed to support the systemic ventricle. A new type of right ventricular assist device driven by an impeller pump was successfully used for 79 hours after emergency revascularisation after right coronary occlusion. Despite renal failure requiring haemofiltration the patient has now fully recovered.

Acute Kidney Injury↗
PubMed1987

Effect of high-dose ibuprofen on 24-hour blood pressure in healthy women.

The nonsteroidal antiinflammatory drug (NSAID) indomethacin has been shown to increase blood pressure in normotensive individuals. The effect of other NSAID on blood pressure has not been as well studied. We evaluated the effects of ibuprofen, an NSAID currently available without a prescription, on 24-hour ambulatory blood pressure in ten young, healthy, normotensive women. Using a randomized, crossover, double-blind design, subjects received ibuprofen 800 mg and a placebo identical in appearance to ibuprofen three times a day for eight days with a washout period between regimens. Subjects were instructed to follow a no-added salt diet during the study. Twenty-four-hour blood pressure monitoring and 24-hour urine collection for prostaglandin E2, creatinine, and sodium were performed on days 1 and 8 of each study week. Tablet counts and a 40 percent reduction in urinary prostaglandin E2 documented compliance with ibuprofen. Ibuprofen had no significant effect on systolic or diastolic blood pressure at any hour during the 24-hour period. Mean blood pressure for the 24-hour period was 112/73 and 111/73 mm Hg on day 1 and 111/73 and 112/73 mm Hg on day 8 for placebo and ibuprofen, respectively. We conclude that ibuprofen at doses as high as 2400 mg/d for up to seven days has no effect on blood pressure in normotensive women. Further studies are needed in hypertensive subjects.

Adult↗
PubMed1986

Severe primary hyperparathyroidism in a neonate with two hypercalcemic parents: management with parathyroidectomy and heterotopic autotransplantation.

A neonate with severe primary hyperparathyroidism was successfully managed by parathyroidectomy and heterotopic autotransplantation (one third of one gland of the infant was implanted in the forearm). In vitro studies of parathyroid tissue from the infant revealed a severe defect in parathyroid suppressibility. Postoperatively, the infant had modest hypercalcemia, normal serum immunoreactive parathyroid hormone levels, hypermagnesemia, and relative hypocalciuria. The parents were related and both had asymptomatic hypercalcemia with mean serum immunoreactive parathyroid hormone levels that were within the normal range. Similar to the findings in the infant postoperatively, relative hypocalciuria in the presence of hypercalcemia was found in the mother; in contrast, the father had hypercalciuria. The presumed dominantly transmitted hypercalcemia in this kindred is consistent with familial hypocalciuric hypercalcemia with a confounding factor of ethanol possibly accounting for the hypercalciuria in the father.

Acute Disease↗
PubMed1985

Monoclonal antibodies to human growth hormone can distinguish between pituitary and genetically engineered forms.

Monoclonal antibodies (MABs) prepared against human pituitary growth hormone (hGH) have been compared for their binding to pituitary-derived and genetically engineered methionyl growth hormone (met-hGH). The antibodies bind to four non-overlapping epitopes of which two are completely shared with human choronic somatomammotropin (hCS). The determinant defined by MAB NA27 was expressed on met-hGH to a lesser degree than on hGH of pituitary origin. However, another antibody, QA68, which binds to a determinant closely related to NA27, failed to discriminate between hGH and met-hGH. A further two MABs (EB1 and NA71) were similarly ineffective in distinguishing between the two forms of the hormone. The determinant recognized by antibody EB2 was equally represented on hGH and met-hGH when assessed by a liquid-phase radioimmunoassay: however, measurement of the binding in a solid-phase assay resulted in a two-four-fold lower binding to met-hGH. Bioactivity assessed by both an in vitro cell proliferation assay and an in vivo cartilage sulphation bioassay failed to distinguish between the two hormones. It is therefore concluded that the NH2-terminal methionine on bacterially derived growth hormone results in altered antigenicity of the hormone without any measurable effect on bioactivity.

Animals↗
PubMed1984

Factors relating to urine spraying and fighting in prepubertally gonadectomized cats.

The fact that male cats are routinely castrated prior to full sexual maturity for behavioral reasons prompted a survey of the prevalence of these behaviors in prepubertally gonadectomized male and female cats. About 10% of the 134 male and 5% of the 152 female cats studied engaged in spraying on a frequent basis later in adult life. Problem spraying and fighting in males was of the same order of magnitude as in males castrated in adulthood after the problem behaviors had appeared. The age of prepubertal castration, ranging from 6 to 10 months, had no influence on spraying or fighting later in life. It was found that male cats are more likely to spray and fight if they are in households with female cats than with other male cats. With regard to female cats, spraying or fighting was less than that of male cats. Age at the time of gonadectomy was not a factor in their tendency to spray or fight. Possible prenatal masculinization of female fetuses by male fetuses, as revealed by littermate composition, was not a factor in the predisposition of female cats to spray or fight.

Aggression↗