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21.
22.
Permeation of human ovarian tissue with cryoprotective agents in preparation for cryopreservation 总被引:18,自引:10,他引:18
Newton H; Fisher J; Arnold JR; Pegg DE; Faddy MJ; Gosden RG 《Human reproduction (Oxford, England)》1998,13(2):376-380
The recent improvements in the treatment of cancer by chemo- and
radiotherapy have led to a significant increase in the survival rates of
patients with malignant disease, but at the expense of distressing side
effects. One major problem, especially for younger patients, is that
aggressive therapy destroys a significant proportion of the follicular
population, which can result in either temporary or permanent infertility.
Freeze-banking pieces of ovarian cortex prior to treatment is one strategy
for preserving fecundity. When the patient is in remission, fertility
could, theoretically, be restored by autografting the thawed tissue at the
orthotopic site or by growing isolated follicles to maturity in vitro.
Recent studies have found good follicular survival in frozen-thawed human
ovarian tissue but to optimize the process an effective cryopreservation
method needs to be developed. An essential part of such a technique is to
permeate the tissue with a cryoprotectant to minimize ice formation and the
extent of this equilibration is an important determinant of post-thaw
cellular survival. In the current study, we have investigated the diffusion
of four cryoprotective agents into human tissue at both 4 degrees C and 37
degrees C. We have also studied the effect of adding different
concentrations of the non penetrating cryoprotective agent, sucrose, to the
freezing media using the release of lactate dehydrogenase as a measure of
its protective effect. At 4 degrees C propylene glycol and glycerol
penetrated the tissue significantly slower than either ethylene glycol or
dimethyl sulphoxide. At the higher temperature of 37 degrees C all four
cryoprotectants penetrated at a faster rate, however concern about enhanced
toxicity prevents the use of these conditions in practice. Thus, the
results suggest that the best method of preparing tissue for freezing is
exposure for 30 min to 1.5 M solutions of ethylene glycol or dimethyl
sulphoxide at 4 degrees C; this achieved a mean tissue concentration that
was almost 80% that of the bathing solution. We also report that the
addition of low concentrations of sucrose to the freezing medium does not
have a significant protective effect against freezing injury.
相似文献
23.
24.
WOLFRAM GRIMM JÜRGEN HOFFMANN ULRICH KÖHLER JÖRG HEITMANN JÖRG H. PETER PETER VON WICHERT BERNHARD MAISCH 《Journal of sleep research》1995,4(S1):160-165
SUMMARY Twelve patients (aged 48 ± 12 y) with ventricular asystole of >3s due to complete atrioventricular (AV) block ( n = 8), sinoatrial (SA) block or sinus node arrest ( n = 3) or both ( n = 1) associated with obstructive sleep apnoea underwent invasive electrophysiological evaluation of sinus node function and AV conduction properties before and after administration of atropine (0.02 mg kg-1 ). Ventricular asystole lasted for 5.9 ± 2.8 s (range 3.1–13 s). Sinus node function was assessed by measurement of sinus node recovery time, sinoatrial conduction time, and the response of sinus rate to atropine. Parameters of AV-conduction assessment included AH- and HV-intervals, AV- and VA-Wenckebach periods, and effective refractory period of the AV node before and after atropine. Sinus node function was normal in 11 of the 12 study patients and moderately abnormal in 1 patient. AV-nodal function was normal in 8 patients and moderately abnormal in 4 patients. A slightly prolonged HV-interval (59–63 ms) was present in 6 patients. Intra- or infra His block was not observed in any patient. In conclusion, normal or only moderately abnormal electrophysiological findings in patients with sleep apnoea-associated ventricular asystole suggest that a neurally mediated cardioinhibitory reflex may cause ventricular asystole in these patients. This sleep apnoea-triggered 'vasovagal' reflex may unmask pre-existing mild to moderate structural abnormalities of the AV conduction system. 相似文献
25.
Arbour NC; Zlotogora J; Knowlton RG; Merin S; Rosenmann A; Kanis AB; Rokhlina T; Stone EM; Sheffield VC 《Human molecular genetics》1997,6(5):689-694
Achromatopsia is an autosomal recessive disease of the retina,
characterized clinically by an inability to distinguish colors, impaired
visual acuity, nystagmus and photophobia. A genome-wide search for linkage
was performed using an inbred Jewish kindred from Iran. To facilitate the
genome-wide search, we utilized a DNA pooling strategy which takes
advantage of the likelihood that the disease in this inbred kindred is
inherited by all affected individuals from a common founder. Equal molar
amounts of DNA from all affected individuals were pooled and used as the
PCR template for short tandem repeat polymorphic markers (STRPs). Pooled
DNA from unaffected members of the kindred was used as a control. A
reduction in the number of alleles in the affected versus control pool was
observed at several loci. Upon genotyping of individual family members,
significant linkage was established between the disease phenotype and
markers localized on chromosome 2. The highest LOD score observed was 5.4
(theta = 0). When four additional small unrelated families were genotyped,
the combined peak LOD score was 8.2. Analysis of recombinant chromosomes
revealed that the disease gene lies within a 30 cM interval which spans the
centromere. Additional fine-mapping studies identified a region of
homozygosity in all affected individuals, narrowing the region to 14 cM. A
candidate gene for achromatopsia was excluded from this disease interval by
radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an
essential first step in the identification of the disease-causing gene.
相似文献
26.
27.
Fertilization and early embryology: Influence of maternal age on meiotic spindle assembly oocytes from naturally cycling women 总被引:1,自引:0,他引:1
Battaglia D.E.; Goodwin P.; Klein N.A.; Soules M.R. 《Human reproduction (Oxford, England)》1996,11(10):2217-2222
To examine the effects of maternal ageing on the meiotic apparatus,we obtained oocytes from naturally cyding women in two age groups,including younger (aged 2025 years) and older (aged 4045years) women. Using high- resolution confocal microscopy weobtained a detailed picture of the meiotic spindle and chromosomeplacement during various phases of meiosls. Our data revealedthat the meiotic spindle in older women is frequently abnormal,both with regard to chromosome alignment and the micro- tubulematrix that comprise the meiotic spindle. The spindle in 79%of the oocytes from the older group exhibited abnormal tubulinplacement and one or more chromosomes were displaced from themetaphase plate during the second meiotic division. In contrast,only 17% of the oocytes from the younger age group exhibitedaneuploid conditions. The majority of eggs from this group possesseda well ordered, meiotlc spindle containing chromosomes thatwere fully aligned within a distinct metaphase plate in thespindle. Chromosome management during meiosis is directed bymicrotubule assembly within the spindle. These data suggestthat the regulatory mechanisms responsible for assembly of themeiotic spindle are significantly altered in older women, leadingto the high prevalence of aneuploidy. 相似文献
28.
Battaglia TC Clark RT Chhabra A Gaschen V Hunziker EB Mikic B 《Connective tissue research》2003,44(5):218-224
The mechanisms by which tendon strength is established during growth and development and restored following injury are not completely understood and are likely to be complex, multifactorial processes. Several studies examining the relationship between mechanical behavior and ultrastructural characteristics of tendons and ligaments during growth and maturation suggest that collagen fibril diameter is strongly correlated with tendon strength. Because of the similarities between development and repair processes of musculoskeletal tissues, increases in tendon strength during healing may be related to increases in fibril ultrastructural parameters such as fibril size, numerical density, and area fraction. In this study, we compared murine Achilles tendons at various time points after tenotomy with sham-operated controls in tensile tests to failure and examined tendons using electron microscopy to assess collagen fibril ultrastructure. We found that in the 6-week period following Achilles tenotomy, fibril mean diameter remained significantly smaller than sham-side diameter by a factor of 2-3. Despite the persistently small fibril size, increasing numerical density resulted in a gradual increase in fibril area fraction. Biomechanical strength did not reach that of intact tendons until some time between 5 and 7 weeks, approximately the same time period when fibril area fraction began to approach sham values. These data suggest that parameters other than collagen fibril size are most responsible for increased tendon strength during healing. 相似文献
29.
30.
Russell EJ; Geremia GK; Johnson CE; Huckman MS; Ramsey RG; Washburn-Bleck J; Turner DA; Norusis M 《Radiology》1987,165(3):609-617
Sixteen patients with suspected cerebral metastases were studied with magnetic resonance (MR) imaging before and after the intravenous administration of 0.1 mmol/kg of gadolinium diethylenetriaminepenta-acetic acid. The images were interpreted blindly by two neuroradiologists; all clinical, radiologic (computed tomographic and MR imaging), and pathologic data were reviewed to arrive at a final "best diagnosis," which was then compared with the prior blinded interpretations. Of seven patients found to have multiple metastases, six (86%) had at least one tumor nodule depicted by postinfusion MR imaging that was missed by one or both observers on review of preinfusion images alone. Lesions missed on preinfusion studies were usually small nodules hidden by or not detected next to regions of high-signal edema thought to be related to the adjacent tumor nodule. The authors believe that contrast enhancement improves detection of metastatic foci with MR imaging and that the findings indicate broader implications for the detection of multiple lesions from other causes. 相似文献