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Biomedical subjects

J M Cummins

Publications and source records attributed to J M Cummins.

At least 19 recordsLinked to original sources
PubMed2006

Implications of micro-RNA profiling for cancer diagnosis.

Micro-RNAs (miRNAs) are a large class of small non-coding RNAs that regulate protein expression in eucaryotic cells. Initially believed to be unique to the nematode Caenorhabditis elegans, miRNAs are now recognized to be important gene regulatory elements in multicellular organisms and have been implicated in a variety of disease processes, including cancer. Advances in expression technologies have facilitated the high-throughput analysis of small RNAs, identifying novel miRNAs and showing that these genes may be aberrantly expressed in various human tumors. These studies suggest that miRNA expression profiling can be correlated with disease pathogenesis and prognosis, and may ultimately be useful in the management of human cancer.

Gene Expression Profiling↗
PubMed2004

The role of mitochondria in the establishment of oocyte functional competence.

Mitochondria are maternally inherited, semi-autonomous organelles with their own genomes (mtDNA), largely responsible for the generation of energy in the form of cellular ATP. However, mitochondrial replication and transcription of mtDNA do not commence until well into embryonic differentiation. This means that the oocyte needs to contain sufficient stocks of functioning mitochondria to fuel the first few days of embryonic development. In this review, I examine how qualitative and quantitative aspects of mitochondria help us define the notion of functional competence.

Female↗
PubMed2003

Use of a new drug delivery formulation of the gonadotrophin-releasing hormone analogue Deslorelin for reversible long-term contraception in male dogs.

In the present study, we tested the effect of treatment with a slow-release implant containing the gonadotrophin-releasing hormone agonist Deslorelin(TM) (Peptech Animal Health Australia, North Ryde, NSW, Australia) on pituitary and testicular function in mature male dogs. Four dogs were treated with Deslorelin (6-mg implant) and four were used as controls (blank implant). In control dogs, there were no significant changes over the 12 months of the study in plasma concentrations of luteinising hormone (LH) or testosterone, or in testicular volume, semen output or semen quality. In Deslorelin-treated dogs, plasma concentrations of LH and testosterone were undetectable after 21 and 27 days, testicular volume fell to 35% of pretreatment values after 14 weeks and no ejaculates could be obtained after 6 weeks. Concentrations returned to the detectable range for testosterone after 44 weeks and for LH after 51 weeks and both were within the normal range after 52 weeks. Semen characteristics had recovered completely by 60 weeks after implantation. At this time, the testes and prostate glands were similar histologically to those of control dogs. We conclude that a single slow-release implant containing 6 mg Deslorelin has potential as a long-term, reversible antifertility agent for male dogs.

Animals↗
PubMed2002

Mitochondrial DNA polymorphisms and fertility in beef cattle.

Four hundred and twenty-two beef cattle of two different breeds (purebred Hereford and composite multibreed) were characterized by polymerase chain reaction-restriction fragment length polymorphism, using the restriction enzymes ApaI, AvaII, HindIII, PstI, SpeI, SspI and TaqI in two regions (the D-loop and the ND-5 gene) of mitochondrial DNA. The association between molecular haplotypes and records on calving rate, defined as the mean number of live calves born per year over 4 years, were examined by analysis of variance. A significant association was found between calving rate and mitochondrial polymorphisms in both breeds. This may have implications for genetically improving cow fertility.

Animals↗
PubMed2001

Cytoplasmic inheritance and its implications for animal biotechnology.

At fertilization, the mammalian sperm transmits the haploid paternal genome. However, it also carries a variety of other factors into the oocyte that have the potential to affect embryo development. These include mRNAs left over from spermatogenesis, mitochondria with their own DNA, cytoskeletal and contractile elements, remnants of the sperm plasma membrane and, in many species, the sperm centriole. While most of these elements are eliminated, some play essential roles in early embryogenesis. In this review, I summarize the latest information on these phenomena and indicate some of the implications for animal biotechnology and, in particular, cloning.

Animals↗
PubMed2001

Differentially expressed DNA sequences following recovery from unilateral testicular torsion in rat.

The molecular response during recovery from torsion-induced stress in the testis is diverse with a variety of mechanisms. In this study, using unilateral testicular torsion in rat as a model, we used subtractive hybridisation to identify differentially expressed DNA sequences in the torsioned and control testes. Three genes were identified as being down regulated in the torsioned testis compared with controls: Control Testis genes 1, 2 and 3 (CT1, CT2 and CT3). Two genes were up regulated in the torsioned testes: Torsioned Testes genes 1 and 2 (TT1 and TT2). Differential expression was confirmed by Reverse Northern blot analysis. An homology search revealed that CT1 had 88% homology with rat metallothionein cDNA; CT2 had 81% homology with rat cell surface antigen in MHC class I, but no homology could be found for CT3. TT1 had 92% identity with rat Rieske iron-sulphur protein mRNA whereas TT2 had 73% identity with a human clone of unknown function (RP 11-252D22). These results indicate that changes in gene expression occur following torsion induced stress, and that identification of differentially expressed genes may provide insights into the mechanisms of cellular tissue damage in this model.

Animals↗
PubMed2001

Use of orally administered anhydrous crystalline maltose for relief of dry mouth.

OBJECTIVES: To examine the safety and efficacy of anhydrous crystalline maltose (ACM) for treatment of dry mouth. DESIGN: ACM was delivered orally as a 200-mg lozenge given three times daily over a 12-week (study Alpha) or 24-week (study Omega) period to a total of 22 and 97 subjects, respectively. All participants had prominent complaints of persistent dry mouth associated with primary Sjögren's syndrome. Patients were examined every 4 weeks in study Alpha and every 6 weeks in study Omega. SETTINGS: Patients were seen in outpatient clinics at a total of 33 sites within the United States. OUTCOME MEASURES: Unstimulated whole saliva output, a measure of basal salivary gland function, was determined at each visit. Symptoms associated with oral and ocular dryness were assessed at the same time with the use of 100-mm visual analog scales. Safety was assessed by physical examination and laboratory studies. RESULTS: During these clinical trials, a majority of subjects demonstrated an increase in unstimulated whole saliva output and the treatment exhibited an excellent safety profile. The ACM treatment in study Omega led to significant improvement in several subjective measures of oral and ocular comfort. CONCLUSIONS: In these two studies, ACM lozenges administered three times daily for 12 or 24 weeks improved salivary output and decreased complaints of dry mouth and eyes. Side effects were minimal, and treatment was without significant adverse events. This safe and simple intervention may provide clinical benefit to individuals with distressing dry mouth symptoms.

Administration, Oral↗
PubMed2001

Quantification of the common deletion in human testicular mitochondrial DNA by competitive PCR assay using a chimaeric competitor.

The "common" 4977 bp deletion in mitochondrial DNA (Delta4977) is commonly used as an indicator of tissue deterioration in ageing and bioenergetic diseases. Deletion levels are normally measured by a serial dilution polymerase chain reaction (PCR) approach, where test reactions are compared with dilutions of control amplifications of DNA from a similar sized stable region of the mitochondrial genome. The end-point of this assay is the dilution that can just detect any PCR product; however, this is an inherently unstable measure. We constructed a chimaeric DNA construct that binds to both control and deletion primers with similar annealing properties. This was used in a competitive PCR assay to quantify Delta4977 in human testicular tissues that had been well-characterized using the serial dilution approach. We found the competitive assay to be highly replicable as it compares the PCR product of the construct with that of test DNA samples during the linear growth phase of the PCR reaction. Moreover, the serial dilution assay was shown to significantly overestimate the amounts of deleted mitochondrial DNA present. The assay promises to throw new light on the role of mitochondrial DNA deletions in tissue dysfunction and ageing, as such deletions can now be determined with high accuracy and repeatability and is much cheaper to apply than real-time fluorescent quantitative PCR.

DNA, Mitochondrial↗
PubMed2000

Torsion-induced injury in rat testes does not affect mitochondrial respiration or the accumulation of mitochondrial mutations.

Male rats were subjected to 1 h testicular torsion of the spermatic cord or 1 h torsion followed by detorsion and recovery up to 4 weeks. The extent of tissue damage was evaluated by a testicular biopsy score count and mitochondrial function. Torsion for 1 h followed by detorsion induced significant morphological damage, which became more severe with longer periods of recovery. This morphological damage could not be correlated with mitochondrial damage as assessed by measuring the 4834 bp mitochondrial DNA 'common deletion' using a quantitative competitive polymerase chain reaction (PCR) assay. Mitochondrial respiratory chain activity, as measured by mitochondrial oxygen consumption using an oxygen electrode, did not vary between the treated animals and the controls. We conclude that the common mitochondrial DNA deletion and oxygen consumption are not good indicators of testicular damage induced by torsion.

Animals↗
PubMed2000

Fertilization and elimination of the paternal mitochondrial genome.

With rare exceptions, mammalian mitochondria are inherited through the female. This probably serves to minimize lethal cytoplasmic gene competition and to prevent the inheritance of sperm mitochondrial DNA that has been subject to degradation by free radicals. In general, organisms are intolerant of mitochondrial heteroplasmy and, when this occurs in humans, it frequently presents as progressive and lethal bioenergetic or neurological disease. The mitochondria of spermatozoa are specifically destroyed by proteolysis in early embryonic development, in mice at the 4- to 8-cell transition. While there are concerns in human assisted reproduction that microinjection of abnormal or immature sperm cells could lead to lasting harm in the offspring through transmission of abnormal mitochondria, there is no clinical evidence to support this. There is more potential for harm through attempts to 'rescue' poor quality oocytes by cytoplasmic or nuclear transfer, as it is not currently possible to control the final fate of the donated mitochondria in relation to nuclear-mitochondrial interactions or the embryonic axes. Moreover, the balance between nuclear and mitochondrial genes and the role of cytoplasmic factors in epigenesis are still poorly understood. The future challenge for biologists is to comprehend the nature of the selective destruction of paternal mitochondria, as it appears to be a species-specific recognition phenomenon.

Animals↗
PubMed1999

Fate of genetically marked mitochondrial DNA from spermatocytes microinjected into mouse zygotes.

Cytoplasts from single spermatocytes of NZB/BinJ mice were separated from the nuclei and individually microinjected into B6D2F1 (C57BL/6 x DNBA/2J) hybrid embryos at the pronuclear stage (20 h after hCG injection). Of 363 zygotes injected, 311 (86%) survived and developed. From these experiments, we transferred 222 embryos into 20 pseudopregnant recipients. Eighteen (90%) became pregnant and 82 pups were born (37% of transfers). Mitochondrial DNA (mt DNA) from the NZB/BinJ strain lacks a RsaI restriction site and can thus be distinguished from the host embryo following PCR amplification. We were unable to detect the transferred mtDNA in blastocysts on day 4-5 after injection. Nor could we detect NZB/BinJ mtDNA in placentae, nor in tissues from mice born to host mothers following the transfer of blastocysts that developed from injected zygotes. Rejection of paternal mitochondria by the embryo normally occurs at the 4- to 8-cell stage in mice and is apparently dependent on mutual recognition between the mitochondria and the nuclear genome. We conclude that this mechanism has probably already developed by the time the germ cells have become committed to meiosis.

Animals↗
PubMed1999

Oral use of interferon.

Interferon-alpha (IFN-alpha) given orally has biological activity in humans and other animals. The dose providing the most benefit delivers IFN-alpha to the oral mucosa in a concentration (10(2)-10(3) IU), similar to that naturally produced in the nasal secretions during respiratory infections. In contrast, conventional IFN therapy employs parenteral doses of > 10(6) IU and, for this reason, orally administered IFN therapies have been called low-dose treatments. Efficacy in both animal disease models and human studies has been reported, and the mechanisms whereby oral administration has a systemic effect are under active study in a number of laboratories.

Administration, Oral↗
PubMed1999

Natural human interferon-alpha administered orally as a treatment of bovine respiratory disease complex.

Natural human interferon-alpha (nHuIFN-alpha) from three sources was given orally to 368 calves experiencing a natural outbreak of bovine respiratory disease complex (BRDC). In one study, 200 calves were given one treatment daily for 3 days of placebo or 20, 200, or 2,000 IU of nHuIFN-alpha before shipment. Calves treated with 20 or 200 IU had a significant (p < 0.05) weight gain benefit for the first 21 days in the feedlot, if they had rectal temperatures <40 degrees C when treated with nHuIFN-alpha. In a second trial, 168 mixed-breed calves (five groups randomized to 31-36 calves/group) were treated with one dose of placebo or 200 or 400 IU of nHuIFN-alpha after shipment to the feedlot. Using this regimen, a dose of 200 IU per calf significantly (p < 0.08) decreased the number of sick calves per group and delayed development of BRDC. Results of these studies demonstrate that oral administration of nHuIFN-alpha, which may partially mimic the nasally secreted IFN response reported during BRDC, may be beneficial in cattle.

Administration, Oral↗
PubMed1999

Single-step method for the determination of the amount of the common deletion in mitochondrial DNA.

A fluorescent-based quantitative PCR assay to measure the percentage of the common deletion in rat mitochondria is reported. The amount of the common deletion is measured relative to the amount of total mitochondrial (mt)DNA. The use of a heterologous competitor construct allows the reaction to be monitored to ensure that exponential accumulation of products occurs. The use of fluorescence-labeled primers provides a safe and sensitive means to quantify products without any adjustment for size. This assay will allow the quantitative determination of the common deletion with one dilution range.

Animals↗
PubMed1998

Fate of microinjected spermatid mitochondria in the mouse oocyte and embryo.

Mouse round spermatids labelled with MitoTracker were microinjected into Sr(2+)-activated mouse oocytes. The labelled mitochondria were tracked up to the morula/blastocyst stage using fluorescence microscopy. The overall incidence of embryos with labelled mitochondria fell from 80% in the 1-cell zygote to 25% in 2-cell, 9% in 4-cell and approximately 1% in 8-cell or later stages. Thus it appears that almost all round spermatid mitochondria finally disappear from embryos during the 4-cell to 8-cell transition, as happens for mature spermatozoa (Cummins et al. Zygote 1997, 5:301-8). The spermatid mitochondria remained tightly bound together during this process. In contrast, labelled primary spermatocyte and cumulus mitochondria dispersed rapidly throughout the oocyte cytoplasm within 3 h. We hypothesise that spermatid mitochondria may be bound together by cytoskeletal elements produced in the early haploid spermatid. These elements, together with terminal differentiation of the sperm mitochondria, may be central to the processes by which the embryo 'recognises' the sperm mitochondria and inhibits inheritance of paternal mitochondrial DNA. These results suggest that round spermatid injection for infertile men will not pose a significant risk to offspring by transmitting abnormal mitochondrial genomes.

Animals↗
PubMed1998

Low dose oral interferon alpha 2a in HIV-1 seropositive patients: a double-blind, placebo-controlled trial.

Low dose oral interferon alpha has been shown to be of benefit in viral disease in animals. In a double-blind, placebo-controlled trial, 177 patients seropositive for HIV-1 were randomly assigned to receive placebo or recombinant human interferon alpha 2a (rIFN alpha). Endpoints were survival, alteration of disease classification, performance, and changes in CD4+ T cell numbers. There was a trend for improved survival in the group receiving rIFN alpha at the dose of 1.0 IU/lb. The changes in disease classification or in weight were not significantly different. Performance was improved to a greater extent (p=0.1) in the patients who received the two higher rIFN alpha dosages (1.0 IU/lb and 10.0 IU/lb) at 6 months. In addition, the CD4+ T cell count was improved only in the 1.0 IU/lb dose treatment group at 6 months. Treatment with low dose oral interferon at 1.0 IU/lb was associated with improved CD4+ T cell count, performance and a trend toward enhanced survival in HIV seropositive patients. These differences were, however, not statistically significant. A larger study, with better return rate, will be needed to determine whether low dose, oral interferon alpha is actually beneficial for these patients.

Animals↗