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Biomedical subjects

H Newton

Publications and source records attributed to H Newton.

35 records · Page 2Linked to original sources
PubMed1998

Protective effect of vitamin E on ischaemia-reperfusion injury in ovarian grafts.

Ovarian cortical tissue cryopreservation with subsequent autografting is a potential strategy for the preservation of fertility in patients undergoing systemic chemotherapy and pelvic radiotherapy. Non-vascular implants are first subjected to a period of ischaemia before revascularization and are, therefore, vulnerable to ischaemia-reperfusion injury from reactive oxygen species. Ischaemia-reperfusion injury was investigated during the first week after surgery in murine ovarian grafts and human ovarian xenografts in mice with severe combined immune deficiency (SCID) by measuring total lipid peroxides and malondialdehyde concentrations with a colorometric assay. The effects of administering an antioxidant, vitamin E, on these concentrations were also tested. Products of lipid peroxidation were higher in non-supplemented murine autografts compared with control ovaries (P < 0.05), and were significantly reduced on day 3 by vitamin E administration (P < 0.05). Similarly, in human xenografts, there was a significant reduction in lipid peroxidation with vitamin E administration. These results correspond to a significantly greater total follicle survival in the murine grafts of the supplemented group (45 versus 72%; P < 0.05). They suggest that antioxidant treatment improves the survival of follicles in ovarian grafts by reducing ischaemia-reperfusion injury.

Adult↗
PubMed1997

Isolation and characterization of primordial follicles from fresh and cryopreserved human ovarian tissue.

OBJECTIVE: To develop an efficient isolation technique for human primordial follicles. DESIGN: Prospective, experimental study of ovarian biopsies collected from healthy women undergoing elective cesarean section. Ovarian blocks either were fixed for histology and follicle counting or partially disaggregated with type 1A collagenase before or after cryopreservation. After partial disaggregation, follicles were isolated by microdissection. SETTING: Leeds General Infirmary. MAIN OUTCOME MEASURE(S): Follicle viability was assessed with live-dead stains using 5-(and 6-) carboxyfluorescein diacetate, succinimidyl ester and propidium iodide, respectively, and using electron microscopy. The numbers recovered were expressed as a percentage of the numbers of primordial follicles in comparable blocks of tissue and the viability of the whole follicle and oocyte were scored separately. RESULT(S): On average, 18.0 +/- 3.8 and 15.9 +/- 2.2 (mean +/- SEM) follicles per block were recovered from fresh and cryopreserved ovarian tissue, respectively, corresponding to recovery rates of 57.9% +/- 8.8% and 56.2% +/- 16.7%. In the fresh group, the percent viability of whole follicles and oocytes were 71.6% +/- 2.4% and 91.3% +/- 2% compared with 71.5% +/- 4.7% and 95% +/- 4.3% in the frozen-thawed group. Electron microscopy confirmed that the majority of the cells lacked ultrastructural signs of damage after isolation and cryopreservation. CONCLUSION(S): Primordial follicles can be isolated from fresh and cryopreserved human ovarian tissue with similar high efficiency and viability rates.

Adult↗
PubMed1996

[Follicle freezing and autografting. A new method of medically assisted procreation?].

Although frozen human follicles were shown to be viable after thawing, more than forty years, the low yield of primordial follicles after cryopreservation has greatly limited research in this area. The aim of freezing follicles is to stock a patient's ovocytes before potentially destructive therapy for cancer then to reimplant the follicular tissue after successful treatment. The patient's ovulatory capacity would then theoretically be restored, allowing natural or possibly in vitro fertilization. As have other teams, we recently renewed work in cryopreservation of follicles in experimental models in search for a better cryopreservation agent and have had encouraging results suggesting that primordial human follicles or ovarian fragments can be grafted successfully after cryopreservation. Questions still under study include the optimal site for implantation, the survival time for grafts and the quantity of follicles needed to achieve pregnancy. Work on large animal models or xenografts of human tissues on immunotolerant animals may provide further insight. The possibilities of grafting primordial follicles, either alone or within ovarian tissue, may raise hope for many women, although new questions such as an age limit for reimplantation and use of allografts requiring preparation with major immunosuppressive therapy require further debate.

Animals↗
PubMed1996

Low temperature storage and grafting of human ovarian tissue.

Ovarian tissue storage at low temperatures is a promising new method for protecting young cancer patients from the sterilizing effects of chemotherapy and/or radiotherapy. Tissue can be stored and returned to the body in due course as a thin cortical graft since the primordial follicles are distributed peripherally and are relatively resistant to ischaemia. Slices of tissue donated by healthy patients were trimmed to a uniform size and preserved by slow freezing to liquid nitrogen temperatures for up to 2 months in one of the following cryoprotectants: dimethylsulphoxide, ethylene glycol, glycerol, propylene glycol. Their viability was assessed by counting follicles in histological sections 18 days after grafting under the kidney capsules of severe combined immunodeficiency (SCID) mice, and the results were expressed as percentages of the numbers in comparable pieces of ungrafted tissue. While only 10% of the total number of follicles was found in the glycerol group compared to controls, significantly higher percentages (44-84%) survived cryopreservation in the other media. The tissues were sterile when frozen and thawed without a cryoprotectant. These results suggest that if comparable results could be achieved by autografting, a patient's fertility should be safeguarded from cytotoxic treatment.

Adolescent↗
PubMed1991

Stereotypes of pilots and apprehension about flying with them: a study of commercial aviation scenarios.

This study explored the effects of gender, experience, and performance of a commercial aviation pilot on concern of passengers about flying with him or her. It used scenarios that represented two aspects of pilot behavior: skill and judgment. We cast 112 adult subjects in the role of passengers. They read vignettes that described their captain and the flight in a 2 x 2 x 2 factorial design (male or female, newly promoted or veteran captain, strong or weak performance). Results showed that of the three manipulated variables, only pilot performance had a statistically significant main effect upon apprehension about making a continuation flight with the pilot (F = 41.52; p less than or equal to 0.001 for the skill scenario and F = 41.73; p less than or equal to 0.001 for the judgment scenario). Statistical interactions showed that the level of passenger concern was not based entirely on pilot performance. For instance, on the skill scenario, when a female pilot performed well, her rating was higher than that of an equally performing male, but when she performed poorly, her rating was lower than his (F = 5.38; p less than or equal to 0.02).

Adult↗
PubMed1990

Effect of hydrocephalus on prostaglandins and thromboxane B2 in ventricular cerebrospinal fluid.

The concentrations of prostaglandin F2 alpha, prostaglandin E2, 6-ketoprostaglandin F1 alpha (prostacyclin metabolite), and thromboxane B2 were assayed in ventricular cerebrospinal fluid obtained from 28 patients with hydrocephalus (17 obstructive, 11 communicating). Seven patients received dexamethasone or hydrocortisone on the day of sampling. No patient received nonsteroidal anti-inflammatory compounds for 48 hours before sampling. The median values did not differ significantly between the two types of hydrocephalus or from the concentrations in lumbar cerebrospinal fluid obtained from patients without intracranial pathology during lumbar myelography for possible lumbar disc disease. Hence, there is no evidence that eicosanoids accumulate in the ventricles in hydrocephalus, and it is unlikely that they have a significant role in its symptomatology.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

The contribution of dietary vitamin D and sunlight to the plasma 25-hydroxyvitamin D in the elderly.

Total plasma 25-hydroxyvitamin D (25-OHD) and its components 25-OHD2 and 25-OHD3 were measured during the winter in young and elderly healthy persons and in elderly women patients in a long-stay mental hospital. The long-stay patients had no exposure to sunlight or other ultraviolet irradiation, but their diet alone maintained an average total 25-OHD level of 16 nmol/l (range, 10.3-26.5 nmol/l), with most values within the ranges observed in the other two groups, although the average value was lower. The plasma 25-OHD2 which is derived exclusively from vitamin D2 in the diet was similar in all three groups and the vitamin D intake was also similar in the two elderly groups. 25-OHD3 is obtained from the diet as well as from the skin and in the elderly patients the diet alone maintained equal concentrations of 25-OHD2 and 25-OHD3. These findings taken together suggest that the diet accounted for 70 per cent of the total 25-OHD in the active elderly in winter compared with 50 per cent in the young subjects. In all our subjects, young or old, the diet was the major source of vitamin D.

25-Hydroxyvitamin D 2↗
PubMedDate not supplied

The cryopreservation of ovarian tissue as a strategy for preserving the fertility of cancer patients.

The cryopreservation of ovarian tissue is a promising new method for conserving the fecundity of young cancer patients from the sterilizing effects of chemotherapy and/or radiotherapy. In murine and ovine studies the orthotopic insertion of frozen-thawed ovarian grafts into sterilized hosts has resulted in the birth of healthy offspring. Examination of human ovarian tissue after cryopreservation has shown that substantial numbers of morphologically normal and viable primordial follicles survive freeze-thawing. To date however, there is no efficient procedure for using the frozen-banked tissue to restore fertility to patients with ovarian failure. Autografting at an orthotopic or heterotopic site has the greatest potential for success but there is concern that the technique may reintroduce malignant cells to patients in remission from disease. Follicle isolation from the thawed tissue and growth to maturity in vitro is a preferable option but at present the technique is in its infancy. This review presents past and present research in the field of ovarian tissue cryopreservation and explores the possible strategies by which frozen-banked tissue from cancer patients could be used to restore fertility.

Animals↗
PubMedDate not supplied

Setopress vs Elastocrepe in chronic venous ulceration.

Venous ulceration is a major problem, particularly in the elderly population. It causes stress to the patient and treatment can be time-consuming. Compression therapy is considered to be the most appropriate non-invasive treatment of venous ulcers. It is generally accepted that composite bandage systems are most efficacious using a long-stretch or short-stretch bandage system. The study reported has compared a long-stretch bandage (Setopress) with a short-stretch bandage (Elastocrepe) over a 16-week period in the treatment of patients with venous ulceration. The trial was a prospective, randomized, observer-blind, parallel group study. Thirty-two patients (male and female) with a total of 39 ulcers completed the trial. After 15 weeks, 11 of 19 ulcers treated with the long-stretch bandage and 7 of 20 ulcers treated with the short-stretch bandage had healed. The differences were not statistically significant. After 15 weeks, the ulcer healing rate for the long-stretch bandage was 58% compared with 35% for the short-stretch bandage. The combined proportion of ulcers healed or improved was statistically significantly greater in the long-stretch bandage group.

Bandages↗
PubMedDate not supplied

Investigating the risk of pressure damage during childbirth.

The incidence of pressure ulceration is well documented within general adult hospital and community healthcare populations (Department of Health (DoH), 1992). However, within maternity units this negative outcome is largely unreported. Indeed, many trusts exclude maternity units from their regular pressure incidence and prevalence monitoring. This article will seek to raise awareness of the potential causes and areas where clinical practices could be reviewed in the light of new evidence.

Adult↗
PubMedDate not supplied

The Theracute alternating pressure replacement mattress.

The use of alternating pressure mattresses is still acknowledged as an effective adjunct in the prevention and treatment of pressure damage; however, with the plethora of equipment now available, there is an increasing need to provide information that supports the practitioners' decisions ensuring individual patients' clinical needs are met. This article reviews a new addition to the Talley Medical range of alternating pressure mattresses, the Theracute mattress replacement system.

Beds↗
PubMedDate not supplied

Improving wound care through clinical governance.

The fundamental role of nurse specialists is to improve and maintain the quality of patient care across the organisation. Heather Newton looks at the specialist nursing role in the light of the clinical governance arrangements.

Benchmarking↗
PubMedDate not supplied

An unusual case of tissue breakdown secondary to TB.

Despite the many advances in technology, research and educational initiatives in tissue viability, wound management remains a complex and challenging area for healthcare professionals. This article describes the management of an unusual groin wound that developed as a result of tissue breakdown secondary to tuberculosis.

Aged↗
PubMedDate not supplied

[Freezing of ovarian tissue and outcome].

In females, aggressive chemotherapy and/or radiotherapy for the treatment of cancer can cause a significant reduction in the size of the follicle population within the ovaries, which may lead to a premature menopause. The cryopreservation of ovarian tissue is a promising new method for conserving the fecundity of these cancer patients prior to therapy. In animal studies the insertion of frozen-thawed ovarian autografts at the orthotopic site has led to a resumption of endocrine function and the restoration of fertility. Experimental studies on human ovarian tissue have indicated that viable and morphologically normal follicles are present after freeze-thawing and furthermore, that these follicles survive grafting beneath the kidney capsules of immunodeficient mice. Although ovarian tissue is now being stored from cancer patients, a procedure for using the banked material to restore fertility has not been established. Autografting has been successful in animal studies, but in cancer patients there is concern that the procedure may reintroduce malignant cells. Follicle isolation for subsequent growth to maturity in vitro is a preferable option, but this technology is in its infancy. This paper reviews past and present research in the field of ovarian tissue cryopreservation and investigates the possible strategies by which the frozen-banked tissue could be used to restore fertility. In addition, the practical aspects of clinical ovarian tissue cryopreservation will be discussed.

Age Factors↗