Type 2 diabetes: the epidemic of the new millennium.

The increasing prevalence of obesity, which has reached epidemic proportions, raises the likelihood that a similar increase in diabetes will follow. Linkage between the two conditions is clear. Overweight is not only an important risk factor for the development of diabetes, but also has a significant impact on progression and complications. Diagnostic criteria for the recognition of diabetes and for monitoring of the disease process will become increasingly important. The role of laboratory evaluation needs to be reassessed in light of new concepts regarding classification and diagnostic criteria. The relative utility of glucose and glycosylated protein measurements should be addressed, particularly the relationship between laboratory findings and clinical guidelines. Blood glucose monitoring depends on establishment of the threshold for diagnosis. Additional issues are bedside monitoring, the goal of noninvasive glucose sensors and targeting of therapy. The laboratory scientist is likely to play a key role in the application of advances in the detection and management of diabetes.

Effect of increasing glucose concentrations on Sertoli cell viability in the nonobese diabetic mouse.

Spermatogenesis is severely altered in the nonobese diabetic (NOD) mouse in the presence of diabetes. When insulin is administered early in the development of diabetic changes, blunting of the testicular damage results, suggesting a direct causal effect of hyperglycemia on the testicular alterations. In view of the key role of Sertoli cells in supporting spermatogenic maturation, it has been speculated that the testicular damage may be mediated via Sertoli cell effects. The present study utilized Sertoli cell cultures to test the effects of different glucose levels on cellular viability. Sertoli cells from NOD and control mice were able to survive at glucose concentrations up to 38 mM, when maintained in culture at constant pH. With higher concentrations, there was a progressive loss of viability, comparable in the test and control animals. Further studies will be needed to determine the specific effect of hyperglycemia on Sertoli cells and the association with spermatogenic alterations in the NOD mouse.

Severe testotoxicosis phenotype associated with Asp578-->Tyr mutation of the lutrophin/choriogonadotrophin receptor gene.

Testotoxicosis is a form of male precocious puberty caused by heterogeneous activating mutations in the gene for the lutrophin/choriogonadotrophin receptor (LHR). A patient with an unusually early and severe presentation of testotoxicosis, including profound Leydig cell hyperplasia, was found to have a sporadic mutation encoding Asp578-->Tyr. The severe testotoxicosis phenotype appears to be related to the strongly activating nature of the Tyr substitution.

Regulation of the onset of meiosis in the developing testis.

Meiotic division begins the process of spermatogenic maturation leading to sperm formation. In contrast to the ovary, in which meiosis is initiated early in development, onset of meiosis in the testis is delayed until the time of puberty. An assay procedure was utilized to evaluate factors responsible for the activation and prevention of meiosis in the developing rabbit testis. Testicular specimens from postnatal rabbits at different ages were used to determine if meiosis-activating substance (MAS) activity and meiosis-preventing substance (MPS) activity could be demonstrated prior to the onset of spermatogenesis. An in vitro system in which undifferentiated gonads from 11.5 day old mouse fetuses are cultured in test and control media was employed. The findings indicate that MAS activity is associated with the onset of spermatogenesis and is also present shortly after birth. Activity of MPS is present throughout much of the prespermatogenic period, with a decline to reach low levels at the onset of spermatogenesis.

Effect of insulin on testicular alterations in the nonobese diabetic mouse.

Severe spermatogenic alterations occur in association with diabetic manifestations in the nonobese diabetic (NOD) mouse. A study was undertaken to determine whether or not administration of insulin during initial appearance of diabetic changes could inhibit the interference with spermatogenesis. Male NOD mice injected with cyclophosphamide to promote onset of overt diabetes were divided into insulin-treated and nontreated groups. Testicular specimens were then examined by light and electron microscopy. Insulin-treated animals showed variable changes ranging from normal spermatogenesis to moderate to severe alterations. Animals with diabetes that did not receive insulin exhibited extensive spermatogenic disruption. The findings indicate a blunting of testicular damage when insulin is administered early in the development of diabetic manifestations. Although spermatogenic abnormalities could not be prevented entirely by insulin treatment, the results provide evidence for a direct metabolic effect on the pathogenesis of the testicular alterations.

Ultrastructure of developing and malignant germ cells.

Ultrastructural studies have provided special insights on the growth and differentiation of normal and neoplastic germ cells. Prespermatogenic germ cells in the fetal and postnatal testis are large spherical to ovoid cells characterized by a central symmetrical nucleus, prominent reticular nucleoli and abundant cytoplasm with accumulation of glycogen and paucity of other organelles. Similar findings have been observed in seminoma and intratubular neoplasia. These observations support origin of the tumours from germ cells at early stages of differentiation. Evidence is presented to suggest that the pathogenesis of germ cell neoplasia involves excessive proliferation of precursor germ cells associated with loss of intercellular communication.

Morphometric study of the prepubertal rabbit testis: germ cell numbers and seminiferous tubule dimensions.

Testes from rabbits aged 1-9 weeks were examined by light microscopy. Changes in seminiferous tubule dimensions, testicular volume, and volume fraction of tubules were assessed. Germ cells and Sertoli cells were counted in round tubular cross sections and total germ cell number in each testis was estimated. Mitotic, meiotic, and degenerative activities of germ cells as well as their basal or central positions within tubules were quantified. A marked, steady increase in testis volume and in tubular length and volume occurred over the prepubertal period; but diameter underwent no significant increase and in fact decreased until week 4. Overall, tubules lengthened 40-fold and testis volume increased 25-fold; the percentage volume of the testis occupied by tubules rose from one-third neonatally to three-fifths at the onset of spermatogenesis. The ratio of germ cells to total tubular (germ and Sertoli) cells was lowest at 3 weeks. However, the total number of germ cells increased little until 3 weeks, after which it rose at a sharp rate commensurate with testis volume. Percentage of germ cells in mitosis peaked sharply at 3 weeks, dropped in subsequent weeks, and then rose at 7 weeks at the initiation of spermatogenesis. Importantly, the surge in mitosis at 3 weeks was followed by a redistribution of germ cells to a predominantly basal location from 3 to 7 weeks. Meiotic activity was sparse at 7 weeks and became abundant by 9 weeks. Germ cell degeneration remained relatively constant during weeks 1 through 6, with an increase at 7 weeks.

Computerized reporting and follow-up of gynecologic cytology.

A system utilizing inexpensive computer hardware to produce high-quality cytology report and to provide an extensive, semi-automated follow-up system is described. Key features of the reports generated are emphasized. The system uses the Bethesda System nomenclature for reporting cytologic findings to a wide range of physicians, from general practitioners to gynecologists to subspecialists in gynecologic oncology.

Gonadal disorders in infancy and early childhood.

Disorders of gonadal development can result from chromosomal, genetic, endocrine, or structural abnormalities. The different conditions may have similar clinical features, but behavior and management will vary depending on the particular diagnosis. Disorders that appear in infancy and early childhood are often associated with ambiguous genitalia or abnormal sexual development. Distinction is made on the basis of cytogenetic, hormonal, and, when indicated, histopathologic studies. The current review groups the different abnormalities in the following categories: chromosomal and genetic disorders; structural defects; defective endocrine function; excessive endocrine activity. The principal conditions found in these categories are discussed in terms of pathogenesis and laboratory procedures required to establish a precise diagnosis.

Human fetal pancreas transplants.

Human fetal pancreatic islet tissue has several advantages as a transplant source for the amelioration of insulin deficiency in patients with Type I diabetes mellitus. It is now possible to obtain viable tissue, store and ship the tissue without adverse effects on the insulin secretory capacity, and transplant either minced tissue or isolated islet-like cell clusters following digestion and culture into animal models or man. A number of centers have undertaken studies of human fetal pancreatic allografts in man. Optimal results have occurred when pooled tissue from six to 20 donors has been implanted and a number of sites have been studied. The author's own experience in four recipients who did not receive immunosuppression has documented insulin secretion for up to 1 year in the absence of an anticytoplasmic islet cell antibody response on the part of the recipients. Nevertheless, the procedure has not resulted in insulin independence for the recipients and the implanted tissue has not secreted insulin in response to a glucose-amino acid challenge in a normal physiologic pattern. Thus, human fetal pancreatic transplantation for the treatment of Type I diabetes remains an experimental approach.

Reproductive toxicity of 2,4-dinitrotoluene in the rat.

The present study was undertaken to evaluate the effects of the chemosterilant 2,4-dinitrotoluene (DNT) on the rat testis. Adult male rats were fed control, or 0.1%, or 0.2% DNT for 3 weeks. An ultrastructural study of the testes was performed, serum was assayed for testosterone and gonadotropins, and sperm reserve count was determined. A marked change in Sertoli cell morphology was found after 3 weeks of 0.2% DNT exposure. Varying sized vesicles associated with swollen mitochondria and distended endoplasmic reticulum were visible in cells from DNT-treated animals. Circulating levels of follicle stimulating hormone and luteinizing hormone were increased in 0.2% DNT-treated animals. Reduced weights of the epididymides and decreased epididymal sperm reserves were observed in DNT-treated animals. These results indicate that DNT is capable of inducing testicular injury, of directly or indirectly disturbing pituitary function, and of exerting a toxic effect at the late stages of spermatogenesis. These findings suggest that a locus of DNT action is the Sertoli cell, resulting in both inhibition of spermatogenesis and changes in testicular-pituitary endocrine activity.

Reproductive toxicity of 2,4-toluenediamine in the rat. 3. Effects on androgen-binding protein levels, selected seminiferous tubule characteristics, and spermatogenesis.

In previous studies we demonstrated reduced fertility, arrested spermatogenesis, and diminished circulating testosterone levels in rats fed 0.03% 2,4-toluenediamine (TDA) for 10 wk. These studies were extended in three experiments by determining TDA effects on androgen-binding protein (rABP) production and on seminiferous tubule structure, and on early changes in testes morphology and spermatogenesis. In the first experiment, rats fed 0.03% TDA for 10 wk showed a 7- to 9-fold increase in rABP content in testicular cytosol or in media of cultured seminiferous tubules, a 4-fold increase in serum rABP, but a two-thirds decrease in epididymal rABP levels. Testes examination by transmission electron microscopy revealed degenerative changes in Sertoli cells with, where present, normal spermatocytes and spermatids. In the second experiment, 0.03% TDA fed for 4, 6, or 8 wk resulted in a doubling of testes/body weight ratios and a highly correlated 2.5- to 2.9-fold increase in seminiferous tubule fluid volume. An approximately 50% decrease in epididymal sperm reserves was found after 6 or 8 wk of TDA exposure. After 10 wk of exposure to 0.03% TDA, testicular weight was the same as in control-fed rats but seminiferous tubule fluid volume was still elevated. These changes in testicular characteristics indicate TDA effects on Sertoli cell function, on RABP release from the testes (and epididymides), and possibly on tubular fluid transport. In the third experiment, rats fed 0.06% TDA for 1 wk showed a 25% decrease in epididymal sperm content, reduced epididymal weight, and minor structural changes in Sertoli cells. After 3 wk of 0.06% TDA feeding, sperm counts were further reduced, and were accompanied by a dramatic increase in testes weight, intense fluid accumulation, and ultrastructural changes in Sertoli cells. No significant changes in serum testosterone levels were noted in the TDA-treated rats. The results of this third experiment demonstrate TDA toxicity on testicular spermatogenesis within 3 wk of TDA feeding. The within 3 wk of TDA feeding. The findings in this study suggest that the early inhibition of spermatogenesis by TDA is mediated through Sertoli cell damage.

Intratubular germ cell neoplasia.

Intratubular germ cell neoplasia is now well established as a precursor to invasive germ cell tumors of the testis. The lesion is usually associated with subsequent development of typical invasive tumors if orchiectomy is not performed. Pathologic findings in intratubular neoplasia consist of germ cell abnormalities within the seminiferous tubules. The atypical cells have large round nuclei, prominent nucleoli, and abundant clear cytoplasm. They have ultrastructural and immunohistochemical characteristics of spermatogenic precursor cells present in the fetal and postnatal testis. Intratubular collections of abnormal germ cells have been found adjacent to invasive germ cell tumors in a high proportion of cases. Intratubular neoplasia occurring in the absence of testicular enlargement has been found in the following situations: cryptorchidism, in testes of some infertile men, dysgenetic testes, and in the contralateral testis following orchiectomy for germ cell cancer. Recognition of intratubular germ cell neoplasia is of special importance because detection of the most common forms of testicular cancer can be accomplished at a preinvasive stage and, therefore, prior to the opportunity for metastasis.

The role of second-look laparotomy in treatment of epithelial ovarian cancer.

Forty-two patients underwent a second-look laparotomy to assess response to systemic chemotherapy for epithelial ovarian cancer. In 20 cases the operation showed no histologic evidence of disease. None of these cases received additional treatment at the time of negative second-look laparotomy. There has only been one recurrence noted in an average follow-up interval of 38.5 months. The remaining 22 cases did have residual carcinoma and 16 have developed progressive carcinoma despite secondary treatment. We found second-look laparotomy to be a safe and reliable assessment tool. However, we could not demonstrate a medical benefit from the procedure.

Comparative studies of normal and neoplastic ovarian germ cells: 1. Ultrastructure of oogonia and intercellular bridges in the fetal ovary.

Electron microscopic studies were performed on human fetal ovaries to gain insight into the process of mitotic proliferation in developing germ cells. Three stages of germ cell differentiation are present during the early gestational period: primitive germ cells, oogonia, and oocytes. Oogonia, representing the mitotic stage of differentiation, are the predominant cell type present between 9 and 12 weeks' gestation and then progressively decrease in number as a result of transformation into oocytes in meiosis and degeneration. Mitotic division of oogonia, which is extensive during the late first and early second trimesters, is characterized by incomplete separation and persistence of intercellular bridges between germ cells. Intercellular bridges were found in large numbers from 10 weeks until the time of follicle formation at midgestation. The bridges contained microtubule arrays consistent with remnants of the spindle apparatus. The findings support the role of germ cell bridges in maintaining coordination of proliferative activity during the early developmental period.

Comparative studies of normal and neoplastic ovarian germ cells: 2. Ultrastructure and pathogenesis of dysgerminoma.

A series of dysgerminomas of the ovary was examined by electron microscopy and the findings were compared with germ cells in the normal developing ovary. The ultrastructural characteristics of the neoplastic cells, including prominent reticular nucleoli and sparsely distributed cytoplasmic organelles, indicated a close resemblance to oogonia present in the fetal ovary. Occasional cells had localized collections of glycogen, resembling primitive germ cells, but the irregular ameboid appearance and eccentric nuclear location characteristic of cells in the early stage were not seen. Ultrastructural features of oocyte differentiation, such as synaptinemal complexes and perinuclear arrangement of mitochondria, were not found in any of the tumors. Intercellular bridges, a frequent finding at the oogonial stage in the normal ovary, were absent in all of the tumors. The lack of intercellular communication could be responsible for uncontrolled mitotic division leading to germ cell neoplasia.

Initiation of oogenesis in the human fetal ovary: ultrastructural and squash preparation study.

Ovaries from 27 human fetuses at less than or equal to 12 weeks' gestational age were examined with electron microscopy and squash preparation studies. The findings demonstrated that meiosis begins in the fetal ovary between 11 and 12 weeks of age. This is several weeks after gonadal sex differentiation, which can be recognized in the testis at 6 weeks. Ovaries at earlier ages included primitive germ cells and oogonia. With advancing fetal age, mitotic activity and germ cell degeneration became increasingly evident. Preleptotene cells were found as early as 9 to 10 weeks, suggesting that meiotic capacity is present soon after gonadal sex differentiation but further progression into meiosis is delayed until some specific inductive influence is exerted.