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Biomedical subjects

J M Lloyd

Publications and source records attributed to J M Lloyd.

At least 19 recordsLinked to original sources
PubMed2006

The Thompson hemiarthroplasty: a new problem for an old favourite.

The Thompson hemiarthroplasty is a popular hip prosthesis. We present two case reports highlighting a significant alteration in the design of the implant which compromised the success of the operations. In recent years the manufacturing process of this prosthesis has changed, with a resultant increase in the volume of the stem of 10 ml. It is essential that manufacturers inform orthopaedic surgeons of any alteration in the design of the implant and supply compatible instrumentation to minimise surgical errors. Surgeons must remain vigilant when checking the compatibility of the trial and definitive prostheses.

Aged↗
PubMed2005

The practice of out-lying patients is dangerous: a multicentre comparison study of nursing care provided for trauma patients.

Pressure for acute hospital beds is a national problem with many acute trauma patients being admitted to non-trauma wards. This prospective multicentre questionnaire study of 220 qualified trauma and non-trauma nurses aims to compare the quality of nursing care that trauma patients receive when admitted to trauma wards and non-trauma wards. The questions included the nursing management of common fractures and post-operative conditions. The completed questionnaires were scored and the results analysed. Hundred percent of the questionnaires were completed and returned. The trauma nurses conveyed the importance of ice (85%) and elevation (97%) in the initial management of limb fractures. This compares with ice (10%) and elevation (50%) on the outlying wards. Trauma nurses correctly monitor for potentially devastating post-operative complications and compartment syndrome 87% of the time compared with 42% on outlying wards. Spinal injuries are managed appropriately 88% of the time on trauma wards compared with 36% on outlying wards. Trauma patients receive better nursing care when admitted to a trauma ward and are nursed by trauma nurses. Many of the out-lying wards provide sub-optimal trauma nursing care and a few are positively dangerous. We suggest that trauma patients should not be nursed on outlying wards.

Acute Disease↗
PubMed2004

Dipeptidase 1: a candidate tumor-specific molecular marker in colorectal carcinoma.

The aim of this study was to identify tumor-specific markers for the detection of rare disseminated colorectal tumor cells in peripheral venous blood and in intra-peritoneal saline lavage samples collected before and after resection of colorectal tumors. Using cDNA micro-array screening, we found dipeptidase 1 (DPEP1) to be highly expressed in colon tumors compared to matched normal mucosa. Relative reverse transcriptase (RT)-PCR showed that DPEP1 was over-expressed by >/=2 fold in colon tumor compared to normal colonic mucosal tissue in 56/68 (82%) patients. Using immunobead RT-PCR, a technique that first enriches for epithelial cells, we found DPEP1 positive cells in intra-peritoneal lavage and venous blood samples from 15/38 (39%) colorectal cancer cases. This is the first report of DPEP1 as a marker for disseminated colon tumor cells.

Adult↗
PubMed2001

The "languid child" and the eighteenth-century man-midwife.

This article addresses the methods used to preserve the life of a sickly neonate--that is, a child described as "languid" in the immediate period after birth. By looking at the work of some seventeenth-century midwifery authors, we can see how a fragile baby was handled in the period before formal training in midwifery and in the appropriate use of forceps. The article assesses the recognized causes of neonatal risk at the time of William Smellie. Examples from the manuscript midwifery case histories of William Hey, F.R.S. (1736-1819), reveal how a provincial man-midwife handled at-risk babies in domiciliary deliveries. The article also places William Hey within the wider group of eighteenth-century men-midwives and those whose work was leading them toward neonatal and infant care. Respect for life, parental love and grief, and the status of men-midwives in the last half of the eighteenth century are discussed.

Equipment Design↗
PubMed2000

Origin of Plasmodium falciparum malaria is traced by mitochondrial DNA.

The origin and geographical spread of Plasmodium falciparum is here determined by analysis of mitochondrial DNA sequence polymorphism and divergence from its most closely related species P. reichenowi (a rare parasite of chimpanzees). The complete 6 kb mitochondrial genome was sequenced from the single known isolate of P. reichenowi and from four different cultured isolates of P. falciparum, and aligned with the two previously derived P. falciparum sequences. The extremely low synonymous nucleotide polymorphism in P. falciparum (pi=0.0004) contrasts with the divergence at such sites between the two species (kappa=0.1201), and supports a hypothesis that P. falciparum has recently emerged from a single ancestral population. To survey the geographical distribution of mitochondrial haplotypes in P. falciparum, 104 isolates from several endemic areas were typed for each of the identified single nucleotide polymorphisms. The haplotypes show a radiation out of Africa, with unique types in Southeast Asia and South America being related to African types by single nucleotide changes. This indicates that P. falciparum originated in Africa and colonised Southeast Asia and South America separately.

Africa↗
PubMed1997

Transplantation of fetal suprachiasmatic nuclei into middle-aged rats restores diurnal Fos expression in host.

In young animals, the suprachiasmatic nuclei (SCN) of the hypothalamus, which are critical circadian pacemakers, exhibit a light-induced diurnal rhythm in Fos expression. The expression of this immediate-early gene has been used as an index of the activity of the SCN and their ability to respond to external cues that entrain them, such as light. In the present study, we show that by the time rats reach middle age baseline Fos expression increases prematurely during the dark and that light-induced Fos expression is blunted and delayed. We also demonstrate that transplantation of fetal tissue containing the SCN into the third cerebral ventricle of middle-aged rats enables aged hosts to regain the ability to exhibit diurnal patterns of Fos expression that are strikingly similar to those observed in young animals. Our findings lead to the following conclusions: 1) the diurnal pattern of activity of SCN cells is blunted in middle-aged rats, and 2) SCN transplants provide unique signals that enable the cellular systems of the host to regain rhythmic functional capabilities. These results provide new insights into the critical active role that the host plays in restoration of function evoked by the presence of a transplant.

Aging↗
PubMed1997

Aging of the female reproductive system: a window into brain aging.

The menopause marks the permanent end of fertility in women. It was once thought that the exhaustion of ovarian follicles was the single, most important explanation for the transition to the menopause. Over the past decade, this perception has gradually changed with the realization that there are multiple pacemakers of reproductive senescence. We will present evidence that lends credence to the hypothesis that the central nervous system is a critical pacemaker of reproductive aging and that changes at this level contribute to the timing of the menopause. Studies demonstrate that an increasing de-synchronization of the temporal order of neuroendocrine signals may contribute to the accelerated rate of follicular loss that occurs during middle age. We suggest that the dampening and destabilization of the precisely orchestrated ultradian, circadian, and infradian neural signals lead to miscommunication between the brain and the pituitary-ovarian axis. This constellation of hypothalamic-pituitary-ovarian events leads to the inexorable decline of regular cyclicity and heralds menopausal transition.

Aged↗
PubMed1994

Decline in immediate early gene expression in gonadotropin-releasing hormone neurons during proestrus in regularly cycling, middle-aged rats.

Female reproductive decline is characterized by a gradual loss of estrous cyclicity due in part to age-related changes in several hypothalamic neurotransmitter systems known to regulate reproductive function. Previously, we have demonstrated that in middle-aged rats that exhibited no changes in the regularity of their estrous cycles, the proestrous LH surge is markedly attenuated. To determine whether these age-related deficits involve alterations in GnRH neuronal activation, we examined expression of the immediate early gene products, c-fos and Jun, in GnRH neurons of young and middle-aged proestrous animals. Regularly cycling young (3- to 4-month-old) and middle-aged (10- to 12-month-old) animals were perfused transcardially at 2300 h on diestrus or at 0230, 0530, 0900, 1400, 1630, 1930, or 2300 h on proestrus, and the brains were processed for dual immunocytochemistry of c-fos or Jun and GnRH. In agreement with earlier studies in young rats, 34 +/- 4% of the GnRH neurons expressed c-fos and 40 +/- 3% expressed Jun during the proestrous LH surge (1630 and 1930 h). However, in the middle-aged animals, there was a dramatic decline in the number of GnRH neurons that expressed c-fos (9 +/- 1%) and Jun (14 +/- 1%) during the LH surge. There were no changes in the number of GnRH neurons between the two age groups. Furthermore, the strong correlation that existed between c-fos expression and serum LH in young animals was lost by the time the animals reached middle age. These data demonstrate that by the time animals reach middle age, there is a significant decline in the number of activated GnRH neurons, which may account for the decrease in the amplitude of the LH surge that precedes the onset of irregular estrous cycles. This could be due to either age-related changes in the GnRH neuron itself or in the neuronal circuitry involved in activation of these neurons.

Aging↗
PubMed1993

Assessment of gene expression and peptide secretion from individual cells.

We have developed an assay that allows one to monitor gene expression in and peptide secretion from individual cells. By combining the reverse hemolytic plaque with in situ hybridization, investigators can quantitate simultaneously the level of gene expression and the level of secretion of a peptide. The method can be used in any system in which an appropriate antibody for the reverse hemolytic plaque assay and probes complementary to the mRNA of interest are available. It can be used to monitor the level of mRNA and secretion of the peptide product, or expression of one gene and the secretion of another peptide. In this paper we will describe the major steps of the method. We have used the pituitary lactotroph as a model to demonstrate the power of this technique. However, we believe that this method may be an important approach to answer many questions regarding the cellular and molecular mechanisms that regulate the coupling of peptide secretion and gene expression at the single cell level.

Animals↗
PubMed1992

Simultaneous monitoring of pituitary hormone secretion and gene expression within individual cells.

We have recently developed a method to simultaneously quantitate the level of gene expression and the level of secretion of a peptide from individual cells. Our approach has been to combine the reverse hemolytic plaque assay sequentially with in situ hybridization. We present data to show how we have used the pituitary lactotroph as a model to demonstrate the power of this technique. However, we are particularly excited about the potential application of this strategy to approach a broad spectrum of questions regarding the cellular and molecular mechanisms that regulate the coupling of peptide secretion and gene expression at the single cell level. The method can be used in any system in which an appropriate antibody for the reverse hemolytic plaque assay and probes complementary to the mRNA of interest are available.

Animals↗
PubMed1992

Vaccine efficacy for reducing turbinate atrophy and improving growth rate in piggeries with endemic atrophic rhinitis.

Two vaccines, based on formalin-killed whole cells of toxigenic Pasteurella multocida type D and Bordetella bronchiseptica combined with a partially toxoided cell extract of P multocida, were prepared with Freund's incomplete adjuvant (vaccine 1) or by alum precipitation (vaccine 2). Each was tested for safety and efficacy in reducing the severity of nasal turbinate atrophy and improving the growth rate of pigs in three Western Australian commercial piggeries with endemic atrophic rhinitis. In safety experiments with vaccine 1, no adverse clinical effects were observed in vaccinated sows or their progeny. Piglets receiving vaccine 2 showed no injection site abnormalities, pyrexia or turbinate atrophy. In field trials, vaccine 1 significantly reduced the prevalence of moderate to severe nasal turbinate atrophy (Done score 3 to 5) when used in two piggeries (A and B). Progeny from vaccinated sows in piggery B also grew significantly faster than controls. When vaccine 2 was used in piggery A at a later date and in another piggery (C), growth rate was not improved in either piggery and the prevalence of moderate to severe turbinate atrophy was reduced only in piggery C.

Adjuvants, Immunologic↗
PubMed1991

Hypothalamic regulatory peptides and their receptors: cytochemical studies of their role in regulation at the adenohypophyseal level.

Hypothalamic regulatory peptides bind to specific receptors on target cells in the pituitary and control secretion. They in turn can be regulated at the pituitary level by steroid and peptide modulators. Affinity cytochemical techniques are important tools for the identification of specific target binding sites for these regulatory peptides. This presentation reviews the work in which potent, biotinylated ligands of gonadotropin releasing hormone (bio-GnRH), corticotropin releasing hormone (bio-CRH), and arginine vasopressin (bio-AVP) were applied to study the target cell responses. Bio-GnRH, bio-CRH, and bio-AVP bind to membrane receptors on specific anterior pituitary cells. Dual labeling for either gonadotropin or adrenocorticotropin (ACTH) antigens further identified the target cells. After 1-3 minutes, the label was in patches or capped on the surface. After 3 minutes, it was internalized in small vesicles and sent to receptosomes and vacuoles in the Golgi complex. Eventually the biotinylated peptides, or a metabolite, was found in the lysosomes (multivesicular bodies) and a subpopulation of secretory granules. The route and rate of uptake was similar to that described for the classical receptor-mediated endocytosis process. In contrast, intermediate lobe corticotropes internalized the bio-CRH in less than 1 minute. The route through the Golgi complex appeared to be bypassed. Instead the labeled peptide was in vesicles, on the membranes of scattered vacuoles, and in multivesicular bodies. Modulation of ligand binding by steroids showed that changes in receptor numbers correlated with changes in the number of cells that bound the ligand. In male rats, dihydrotestosterone reduced the percentage of GnRH-bound cells by 50%. Most of the reduction appeared in cells that stored luteinizing hormone (LH) antigens. In diestrous female rats, estradiol increased the percentage of bio-GnRH-bound cells. However, the steroid decreased the percentage of GnRH-bound cells in cells from proestrous rats. Glucocorticoids decreased the percentage of CRH-bound corticotropes in as little as 10 minutes. Potentiation of secretion by these ligands was correlated with increases in the percentage of ligand-bound cells. AVP pretreatment of corticotropes increased the percentage of cells that bound bio-CRH. It also increased the rate of receptor-mediated endocytosis of CRH and changed the route so that the Golgi complex was bypassed. This effect could be mimicked by activation of its second messengers (calcium and protein kinase C). Similarly, CRH pretreatment increased the percentage of corticotropes that bound AVP. Thyrotropin releasing hormone (TRH) pretreatment also increased the percentage of thyrotropes that bound AVP.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Age-related changes in proopiomelanocortin (POMC) gene expression in the periarcuate region of ovariectomized rats.

Aging of the female reproductive system results in a decline in estrous cyclicity which is due, in part, to alterations in hypothalamic function. Opioid peptides, especially the proopiomelanocortin (POMC)-derived neuropeptide, beta-endorphin, are thought to play a role in maintaining normal patterns of LH secretion. Previous studies have shown that the level of hypothalamic beta-endorphin and POMC messenger RNA (mRNA) decreases in old animals; however, it is unknown whether opioid peptides are involved in age-related reproductive decline. To determine whether POMC gene expression changes with age and is related to reproductive status, we assessed POMC mRNA levels by in situ hybridization histochemistry in the periarcuate region of young (3-4 months), middle-aged (10-12 months), and old (17-19 months) ovariectomized rats. Two methods of quantitation were used: 1) slides were apposed to x-ray film and POMC mRNA levels were quantitated over the entire periarcuate region, and 2) the same slides were dipped in emulsion and the level of POMC was quantitated in individual cells. POMC mRNA levels decreased 20-30% by the time animals were middle-aged, and no further decline was noted in the old animal groups. The decrease in POMC mRNA levels in the middle-aged and old animals occurred regardless of their reproductive status prior to ovariectomy. In addition, there was a 30-40% decline in the number of cells expressing POMC mRNA in middle-aged and old animals, suggesting an overall age-related decline in POMC gene expression in middle-aged and old animals independent of reproductive status.

Aging↗
PubMed1989

Pressures produced in vitro during intraligamentary anaesthesia.

An in vitro investigation measured the pressures produced by an Astra type aspirating syringe (modified Sterling) and a pressure syringe (Ligmaject) during periodontal ligament injections. A pressure transducer (0-6.9 MPa) was adapted to record the pressures generated within both syringes, with the output of the transducer connected to a microcomputer. Thirty-five clinicians (male: female ratio 3:2) were instructed in the technique of the periodontal ligament injection and the pressures that they produced from both syringes were recorded. Measurements of both the peak and time averaged pressures were obtained from computer print-outs of the recordings. Significantly higher pressures (P less than 0.01) were produced with the pressure syringe than with the aspirating syringe. It was also found that male operators produced significantly (P less than 0.1) higher pressure with the aspirating syringe, although there was no significant sex difference (P greater than 0.1) between the pressures recorded with the pressure syringe. Recordings from the pressure syringe revealed that either a multiple high pressure technique or a steady pressure technique was used, the former producing significantly (P less than 0.01) higher pressures.

Anesthesia, Dental↗
PubMed1989

Synovial fluid glycosaminoglycan (acid mucopolysaccharide) analysis in assessment of temporomandibular joint dysfunction. A pilot study.

Temporomandibular joint (TMJ) synovial fluid was aspirated from normal control subjects and patients undergoing surgery for TMJ dysfunction. The glycosaminoglycan (GAG) composition of this fluid was analysed and compared with the clinical diagnosis and histological appearance of the condylar tissues. Changes in GAG composition were observed where a histologically hyperplastic response was seen in joint tissues, but these findings did not necessarily correlate with the initial clinical diagnosis. It is suggested that the fluid composition reflects the current metabolic activities of the tissues and may provide a useful marker of such processes.

Adult↗