Single or multiple oligodendroglial lineages: a controversy

The text books all say oligodendrocytes are the last cell to arise during development. The analysis of the spatio-temporal pattern of expression of plp/dm-20 during embryonic development in both the chick and the mouse provides evidence that the induction of oligodendrocyte occurs much earlier than we thought. In fact, it seems as though these cells must arise nearly simultaneously with neurons and it is just that they do not mature until later. Furthermore, we review the experimental arguments in favor of the existence of at least two, if not more, oligodendrocyte precursor cells: one is defined by the expression of PDGFRalpha, another characterized by expression of plp/dm-20 is independent from PDGF-AA for its proliferation and survival. We then postulate the existence of a third family of yet unknown origin.

Primary squamous cell carcinoma of the parotid gland: the importance of correct histological diagnosis

BACKGROUND

Primary squamous cell carcinoma of the parotid is an uncommon, aggressive malignancy with a poor prognosis. The diagnosis is made after excluding metastasis from other sites in the head and neck or other primary malignancies of the parotid.

METHODS

Tumor registry data from 1974 to 1994 were reviewed at three University of Louisville-affiliated hospitals. Of 370 parotid tumors, 40 (11%) were initially classified as squamous cell carcinoma of the parotid. Chart review and histological specimen re-examination were conducted to confirm diagnosis.

RESULTS

Only 8 (2%) of the 370 cases, were considered true primary squamous cell carcinoma of the parotid. Patients with metastases to the parotid from primary sites within the upper aerodigestive tract or skin of the head and neck region and high-grade mucoepidermoid carcinoma of the parotid were excluded. Facial nerve dysfunction was a presenting complaint in three patients. Two patients presented with American Joint Committee on Cancer (AJC) clinical stage III disease and six with AJC stage IV disease. All patients were treated with total parotidectomy and radiotherapy. One patient (12%) is alive and free of disease. Median survival was 13 months (range, 11 months-7 years).

CONCLUSIONS

Primary squamous cell carcinoma of the parotid is uncommon, occurring in 2% of parotid neoplasms at our institution. This is an aggressive malignancy, usually presenting in advanced stage and with facial nerve involvement or cervical metastases. Prognosis is poor even with radical surgery and adjunctive radiotherapy. Careful clinical and histological review is necessary to differentiate primary squamous cancer of the parotid from metastases or other primary parotid malignancy.

KIAA0369, doublecortin-like kinase, is expressed during brain development

During embryonic development, the cerebral cortex attains its characteristic adult laminated structure. The finding that X-linked lissencephaly patients harbor mutations in the doublecortin gene implicated this gene product in the process of corticogenesis. An autosomal human gene, KIAA0369, with a high level of similarity to doublecortin, has been cloned from human adult brain. This gene product contains a kinase domain in addition to a doublecortin-like domain. In order to evaluate whether this doublecortin-like kinase also plays a role during brain development, we cloned and studied the expression pattern of the mouse homolog. Three cDNA products of this gene were cloned: one, doublecortin-like kinase, the second containing only the doublecortin-like region, and the third containing only the kinase domain, a homolog of the previously cloned rat CPG16 gene. We studied doublecortin-like kinase expression in mouse using Northern blot analysis, in situ hybridization, and Western blot analysis, and conclude that doublecortin-like kinase is expressed in multiple regions of embryonic brain including the developing cerebral cortex.

Subcellular localization of tetanus neurotoxin-insensitive vesicle-associated membrane protein (VAMP)/VAMP7 in neuronal cells: evidence for a novel membrane compartment

The clostridial neurotoxin-insensitive soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptors, tetanus neurotoxin-insensitive (TI)-vesicle-associated membrane protein (VAMP)/VAMP7, SNAP23, and syntaxin 3 have recently been implicated in transport of exocytotic vesicles to the apical plasma membrane of epithelial cells. This pathway had been shown previously to be insensitive to tetanus neurotoxin and botulinum neurotoxin F. TI-VAMP/VAMP7 is also a good candidate to be implicated in an exocytotic pathway involved in neurite outgrowth because tetanus neurotoxin does not inhibit this process in conditions in which it abolishes neurotransmitter release. We have now found that TI-VAMP/VAMP7 has a widespread distribution in the adult rat brain in which its localization strikingly differs from that of nerve terminal markers. TI-VAMP/VAMP7 does not enrich in synaptic vesicles nor in large dense-core granules but is associated with light membranes. In hippocampal neurons developing in vitro, TI-VAMP/VAMP7 localizes to vesicles in the axonal and dendritic outgrowths and concentrates into the leading edge of the growth cone, a region devoid of synaptobrevin 2, before synaptogenesis. After the onset of synaptogenesis, TI-VAMP/VAMP7 is found predominantly in the somatodendritic domain. In PC12 cells, TI-VAMP/VAMP7 does not colocalize with synaptobrevin 2, chromogranin B, or several markers of endocytic compartments. At the electron microscopic level, TI-VAMP/VAMP7 is mainly associated with tubules and vesicles. Altogether, these results suggest that TI-VAMP/VAMP7 defines a novel membrane compartment in neurite outgrowths and in the somatodendritic domain.

Manipulating self-efficacy in the exercise environment in women: influences on affective responses

Self-efficacy was experimentally manipulated in an exercise context, and its effect on affective responses was examined. College women (N = 46) were randomly assigned to a high- or low-efficacy condition, and efficacy expectations were manipulated by means of bogus feedback and graphs depicting contrived normative data. The manipulation successfully influenced affective responses, with participants in the high-efficacy group reporting more positive and less negative affect than did the low-efficacy group. Efficacy was significantly related to feeling-state responses during and after activity but only in the high-efficacy condition. The results suggest that self-efficacy can be manipulated and that these changes are related to the affective experience associated with exercise. Such findings may have important implications for the roles played by self-efficacy and affect in exercise adherence.

Diagnosis of anaplastic large-cell lymphoma, including multifocal osseous KI-1 lymphoma, by fine-needle aspiration biopsy

We present the fine-needle aspiration (FNA) findings of 4 cases of anaplastic (Ki-1) large-cell lymphoma (ALCL). A primary diagnosis of ALCL was made on FNA material in 2 cases, of which one was a multifocal osseous Ki-1 lymphoma. In the other 2 patients who had a known history of ALCL, FNA was used to detect recurrent disease. In all cases, large discohesive pleomorphic cells in the absence of lymphoglandular bodies in the background raised the possibility of a nonhematopoietic neoplasm. Immunochemical staining for CD30 was positive in all cases. The cytomorphologic and immunochemical features are discussed, along with the differential diagnosis of Ki-1 lymphoma. Diagn. Cytopathol. 1999;21:174-179.

Usefulness of ambulatory blood pressure monitoring in pregnant women with type 1 diabetes

OBJECTIVE

Pregnancy in type 1 diabetes is associated with an increased risk of developing pregnancy-induced hypertension (PIH). Ambulatory blood pressure monitoring (ABPM) has been used to screen for preeclampsia in nondiabetic pregnancy. To date, there are no data regarding ABPM during pregnancy in normotensive type 1 diabetic women. This study sought to establish blood pressure (BP) profiles for pregnant type 1 diabetic women using ABPM and determine whether the BP pattern can define a population at risk for developing PIH.

RESEARCH DESIGN AND METHODS

ABPM was carried out for one 24-h period during each trimester--in the first trimester between weeks 7 and 12, in the second trimester between weeks 20 and 24, and in the third trimester between weeks 30 and 34--in 22 normotensive pregnant type 1 diabetic and 10 pregnant nondiabetic women.

RESULTS

The incidence of PIH was fourfold greater in type 1 diabetic women than in control subjects. Diabetic women showed higher daily diastolic BP in the third trimester compared with nondiabetic pregnant women. Diabetic women who developed PIH in the third trimester showed significantly higher BP profiles throughout gestation than those who remained normotensive. Receiver operator characteristics curves for nighttime systolic BP showed the best predictive capacity for PIH, with a cutoff > 105 mmHg (85% sensitivity and 92% specificity).

CONCLUSIONS

Our study confirms the early increase of BP in patients who will develop PIH and suggests that nighttime systolic BP >105 mmHg in the second trimester is a useful predictor of PIH. ABPM may be useful in screening for PIH in pregnant diabetic women.

Early neocortical regionalization in the absence of thalamic innervation

There is a long-standing controversy regarding the mechanisms that generate the functional subdivisions of the cerebral neocortex. One model proposes that thalamic axonal input specifies these subdivisions; the competing model postulates that patterning mechanisms intrinsic to the dorsal telencephalon generate neocortical regions. Gbx-2 mutant mice, whose thalamic differentiation is disrupted, were investigated. Despite the lack of cortical innervation by thalamic axons, neocortical region-specific gene expression (Cadherin-6, EphA-7, Id-2, and RZR-beta) developed normally. This provides evidence that patterning mechanisms intrinsic to the neocortex specify the basic organization of its functional subdivisions.

Evaluation by Vickers indentation of fracture toughness of a phosphate biodegradable glass

Indentation tests are commonly used for the evaluation of fracture toughness of brittle materials, particularly glasses and ceramics, because this technique requires only a small polished area on the specimen surface from which a large number of data points can be generated rapidly. However, a wide variety of equations for the calculation of fracture toughness of ceramic materials by means of Vickers indentation are available. Such equations are obtained phenomenologically and their parameters adjusted in such a way that the KIC values obtained are in good agreement with those obtained by conventional methods. This is the reason why it is necessary to check which type of equation reproduces more accurately the results obtained by means of conventional methods for the material which is going to be investigated. In the present work seven different fracture toughness equations widely used in glass and ceramic studies are considered and the results are compared with those obtained by conventional methods, such as single-edge notch beam (SENB) specimens tested in three-point bending. The role played by the applied indentation load is considered.

Expression pattern of the Tbr2 (Eomesodermin) gene during mouse and chick brain development

The members of the T-box gene family share a highly conserved DNA binding domain named the T-domain, and important developmental functions. Here we report the cloning of chicken Tbr1 and of murine and chicken Tbr2 (orthologs of the Xenopus eomesodermin gene), the mapping of the murine Tbr2 to chromosome 9, and their pattern of expression during mouse and chick embryogenesis. Both Tbr 1 and 2 have a restricted and conserved domain of expression in the telencephalic pallium of the two species. Chick Tbr2 has a specific and dynamic expression in the gastrulating embryo.

Manipulating self-efficacy in the exercise environment in women: influences on affective responses

Self-efficacy was experimentally manipulated in an exercise context, and its effect on affective responses was examined. College women (N = 46) were randomly assigned to a high- or low-efficacy condition, and efficacy expectations were manipulated by means of bogus feedback and graphs depicting contrived normative data. The manipulation successfully influenced affective responses, with participants in the high-efficacy group reporting more positive and less negative affect than did the low-efficacy group. Efficacy was significantly related to feeling-state responses during and after activity but only in the high-efficacy condition. The results suggest that self-efficacy can be manipulated and that these changes are related to the affective experience associated with exercise. Such findings may have important implications for the roles played by self-efficacy and affect in exercise adherence.

Halogenated derivatives of boldine with high selectivity for alpha1A-adrenoceptors in rat cerebral cortex

The selectivity of 3-nitrosoboldine and different halogenated derivatives of boldine (3-bromoboldine, 3,8-dibromoboldine and 3-chloroboldine) for alpha1-adrenoceptor subtypes was studied by examining [3H]-prazosin competition binding in rat cerebral cortex. In the competition experiments [3H]-prazosin binding was inhibited completely by all the compounds tested. The inhibition curves displayed shallow slopes which could be subdivided into high and low affinity components. The relative order of affinity and selectivity for alpha1A-adrenoceptors was 3-bromoboldine = 3,8-dibromoboldine = 3-chloroboldine > boldine > 3-nitrosoboldine. The competition curves for 3-bromoboldine remained shallow and biphasic following chloroethylclonidine treatment. Whereas the relative contribution of the high affinity sites increased, the 3-bromoboldine affinities at its high and low affinity sites remained similar to those obtained in untreated membranes. 3-Bromoboldine, 3,8-dibromoboldine, 3-chloroboldine and 3-nitrosoboldine did not significantly displace [3H]-(+)-cis-diltiazem binding to rat cerebral cortex membranes. This activity was lower than that shown by boldine. Compared to boldine, halogen (bromine or chlorine) substitution at position 3 increases the alpha1A-adrenoceptor subtype selectivity and decreases the affinity for the benzothiazepine binding site at the calcium channel. Further halogen substitution at position 8 did not significantly improve this activity with respect to 3-bromoboldine. In contrast, the NO substitution at position 3 of boldine (3-nitrosoboldine) gives a loss of affinity and selectivity for alpha1-adrenoceptor subtypes.

FGF8 induces formation of an ectopic isthmic organizer and isthmocerebellar development via a repressive effect on Otx2 expression

Beads containing recombinant FGF8 (FGF8-beads) were implanted in the prospective caudal diencephalon or midbrain of chick embryos at stages 9–12. This induced the neuroepithelium rostral and caudal to the FGF8-bead to form two ectopic, mirror-image midbrains. Furthermore, cells in direct contact with the bead formed an outgrowth that protruded laterally from the neural tube. Tissue within such lateral outgrowths developed proximally into isthmic nuclei and distally into a cerebellum-like structure. These morphogenetic effects were apparently due to FGF8-mediated changes in gene expression in the vicinity of the bead, including a repressive effect on Otx2 and an inductive effect on En1, Fgf8 and Wnt1 expression. The ectopic Fgf8 and Wnt1 expression domains formed nearly complete concentric rings around the FGF8-bead, with the Wnt1 ring outermost. These observations suggest that FGF8 induces the formation of a ring-like ectopic signaling center (organizer) in the lateral wall of the brain, similar to the one that normally encircles the neural tube at the isthmic constriction, which is located at the boundary between the prospective midbrain and hindbrain. This ectopic isthmic organizer apparently sends long-range patterning signals both rostrally and caudally, resulting in the development of the two ectopic midbrains. Interestingly, our data suggest that these inductive signals spread readily in a caudal direction, but are inhibited from spreading rostrally across diencephalic neuromere boundaries. These results provide insights into the mechanism by which FGF8 induces an ectopic organizer and suggest that a negative feedback loop between Fgf8 and Otx2 plays a key role in patterning the midbrain and anterior hindbrain.

Mab21, the mouse homolog of a C. elegans cell-fate specification gene, participates in cerebellar, midbrain and eye development

A multitude of regulatory genes are involved in phylogenetically conserved developmental cascades required for the patterning, cell-type specification, and differentiation of specific central nervous system (CNS) structures. Here, we describe the distribution of a mouse transcript encoding a homolog of the C. elegans mab-21 gene. In the nematode tail, mab-21 is required for the short-range patterning and cell-fate determination events mediated by egl-5 and mab-18, two homeobox genes homologous to Abd-B and Pax6, respectively. In mouse midgestation embryogenesis, Mab21 is expressed at its highest levels in the rhombencephalon, cerebellum, midbrain, and prospective neural retina. Our data and the genetic interactions previously documented in the nematode suggest that Mab21 may represent a novel, important regulator of mammalian cerebellum and eye development.

Multiple restricted origin of oligodendrocytes

The plp gene encodes the proteolipid protein and its alternatively spliced product DM-20, major proteins of CNS myelin. In the mouse, plp/dm-20 transcripts are expressed beginning at embryonic day 9.5 (E9.5) by restricted foci of germinative neuroepithelial cells. To determine the identity of the neural precursors expressing plp/dm- 20, a zeomycin resistance gene fused to the lacZ reporter was expressed in transgenic mice under the control of the plp regulatory sequences. In the three different lines generated, the pattern of beta-galactosidase expression was similar and superimposable on the expression pattern of endogenous plp/dm-20. Both in vivo and in vitro, the transgene was expressed by O4(+) pre-oligodendrocytes, and later by RIP+ differentiated oligodendrocytes, but not by neuronal cells, astrocytes, or radial glial cells. After zeomycin selection, a dramatic enrichment in O4(+) pre-oligodendrocytes was observed in cultures derived from E12.5 transgenic embryos. This enrichment indicates the oligodendroglial specification of neural precursors that continuously express plp/dm-20. Early plp/dm-20-expressing precursors, however, appear to be a separate population from previously described PDGFRalpha oligodendrocyte precursors, as shown by the striking differences in their (1) patterns of distribution and (2) responsiveness to PDGF. These data suggest that oligodendrocytes have a plural origin and that early plp/dm-20 defines one of the neural lineages generating oligodendrocytes.

Migration, ethnicity and environment: HIV risk factors for women on the sugar cane plantations of the Dominican Republic

OBJECTIVE

To determine risk factors for HIV infection among women living in the sugar cane plantation communities (bateyes) of a large private sugar cane company in the Dominican Republic.

DESIGN

Cross-sectional study of sexually active female volunteers living in the bateyes.

METHODS

Of 98 bateyes, 23 were randomly selected and visited by a mobile medical unit, to interview, examine and test volunteers for seroreactivity to HIV and syphilis.

RESULTS

The 490 subjects ranged in age from 16 to 72 years (median, 37 years); 53% were born in Haiti, 36% in Dominican Republic bateyes, and 12% elsewhere in the Dominican Republic; 58% had no formal education; and 87% had no income. HIV seropositivity was found in 28 women (5.7%), including 8.8% of those aged < 35 years. By logistic regression analysis, HIV infection was independently associated with age < 35 years [odds ratio (OR), 4.5; P < 0.01), being single with children (OR, 4.3; P < 0.01), more than one lifetime sex partners (OR, 3.4; P = 0.06), engaging in sex during menses (OR, 3.2; P = 0.02), and self-description as a prostitute (OR, 4.4; P = 0.05)1. For Haitian women, those coming to the Dominican Republic alone were more likely to have HIV infection than those coming with a male partner. Less than 4% of women reported condom use at last intercourse.

CONCLUSIONS

Women in the bateyes have a much higher rate of HIV infection than that estimated for women in the general population of Dominican Republic and a rate comparable to that of female sex workers in the Dominican Republic. AIDS prevention in the bateyes should address condom education and distribution as well as employment opportunities and education for women.

Calretinin in pretecto- and olivocerebellar projections in the chick: immunohistochemical and experimental study

Calretinin (CaR) is a calcium-binding protein that is distributed extensively in the central nervous system. It is localized in the cell bodies and neurites of specific neuronal populations and serves, therefore, as a reliable anatomical marker. Some components of the pretectocerebellar projection, which connects specific pretectal nuclei to caudal cerebellar folia, are concerned with the cerebellar control of visual reflexes. We investigated the distribution of pretectocerebellar-projecting neurons in relation to cells that show CaR immunoreactivity. Cells that project to the cerebellar cortex in the diencephalic primary visual nuclei and in other grisea, like the nucleus spiriformis medialis and the nucleus dorsofrontalis, colocalized with those that appeared to be immunolabeled intensely with anti-CaR antiserum. To explore the hypothesis of a common developmental origin of these pretectal cerebellopetal neurons, we also investigated the development of CaR-immunopositive cells in the chick pretectum and the arrival of their fibers in the cerebellum, from 10 days of incubation (stage 36) to posthatching stages. Finally, we analyzed the source of CaR+ climbing fibers and found a subpopulation of CaR+ cells in the inferior olivary nucleus. On the whole, these results suggest that there is a common developmental origin of pretectal cerebellopetal neurons, some of which share the property of CaR expression. The functional significance of this correlation needs to be investigated.

Simultaneous in vivo determination of acetylcholinesterase activity and acetylcholine release in the cortex of waking rat by microdialysis. Effects of VX

We have designed a microdialysis technique to measure acetylcholinesterase (AChE) activity in the cortex of freely moving rats while simultaneously measuring the release of acetylcholine (ACh). Our approach was validated using ethyl S-2-di-isopropylaminoethyl-phosphonothiolate (VX), an irreversible inhibitor of AChE and comparing inhibition measured by this 'in vivo' method with traditional post-mortem assays of AChE activity 120 min after an intraventricular injection of VX. Maximum inhibition of AChE occurred 30 min after injection and was followed by a slow recovery. ACh release reached its maximum 60 min after treatment and then decreased towards normal levels. This method offers a new way to develop medications against poisoning with anticholinesterasic neurotoxic and allows the evaluation of the effects of cholinergic drugs for the treatment of Alzheimer's disease.

Regionalization of the prosencephalic neural plate

Recent embryological studies are beginning to establish that the underlying organization of the forebrain may be reduced to relatively simple elements that are common to all vertebrates. We begin this chapter by reviewing studies that describe the similarities in prospective fate and molecular organization of the developing neural plate in fish, frogs, chickens, and mice. The chapter next addresses mechanisms that regulate regional specification in the anterior central nervous system. There is now evidence that the axial mesendoderm anterior to the notochord (the prechordal plate) has a central role in induction of the floor and basal plate primordia (hypothalamus) of the forebrain. Patterning of the anterolateral neural plate (telencephalon) may be regulated by FGF8 produced in the anterior neural ridge. Thus, the synthesis of information from fate mapping and experimental embryological and genetic studies is illuminating the mechanisms that generate the different components of the forebrain.

Dexamethasone activates expression of the PDGF-alpha receptor and induces lung fibroblast proliferation

Corticosteroids (CSs) are commonly used for anti-inflammatory therapy in asthma and in interstitial lung diseases. In attempting to understand the mechanisms through which CSs control cell proliferation, we have carried out experiments to test the effects of dexamethasone (Dex) on the growth of lung fibroblasts. Using mouse 3T3 fibroblasts as well as early-passage rat lung fibroblasts (RLFs), we show that the quiescent cells in 1% serum or in serum-free media proliferate significantly in response to the addition of 10(-7) to 10(-9) M Dex. Increases as high as fourfold in cell numbers were recorded for the RLFs after 48 h in culture. A polyclonal antibody to the AB isoform of human platelet-derived growth factor (PDGF) blocked the proliferative response. As expected, the fibroblasts produced primarily PDGF-A chain, and the RLFs exhibited few PDGF-alpha receptors (PDGF-R alpha), the receptor type necessary for binding the AA isoform. Accordingly, we determined that Dex upregulated PDGF-R alpha mRNA and protein. Therefore, we can postulate that Dex-induced fibroblast proliferation is mediated, at least in part, by PDGF-AA, which binds to the PDGF-R alpha.

Prevalence of diabetes mellitus and associated cardiovascular risk factors in an adult urban population in Paraguay

A cross-sectional study was conducted on a 20-74-year-old population in an urban white-Hispanic population in Paraguay to determine the prevalence of diabetes mellitus (DM), impaired glucose tolerance (IGT), and associated cardiovascular disease (CVD) risk factors. In total 1606 subjects completed the study (response rate 80.3%; 1094 women, 512 men). The overall prevalences were: DM 6.5%, IGT 11.3%, hypertension 17.1%, and obesity 31.6% with more obesity in women (35.7% vs 22.8%, p < 0.05). Age-standardized prevalences were: DM 6.5%, IGT 13.5% in females and DM 5.5%, IGT 7.2% in males. DM and IGT subjects had two or more CV risk factors significantly more often than the normal population. In conclusion, DM, IGT, hypertension, and obesity are common in this South American Hispanic urban population, particularly in women. Public health measures, such as lifestyle education, are required to decrease these noncommunicable diseases.