The transition to adult income supports for youth that received special education in British Columbia, Canada: A cohort study

Youth in special education have complex needs that are supported across multiple systems. Our research investigates the use of adult income assistance, as one structure that supports youth as they transition to adulthood. We created a cohort of youth (5-22 years old) using linked administrative data from British Columbia government ministries from 1996 to 2018. Youth were grouped by their special education funding (most to least; Level 1, Level 2, Level 3, Unfunded, and no special education). We investigated (1) youth characteristics and service use patterns, (2) which youth used income supports after the child-to-adult transition (19-22 years old), and what youth characteristics and service use patterns were associated with use, and (3) how much income support they used (CAD$). Of 174,527 youth, 254 (0.1%) were Level 1, 6020 (3.4%) were Level 2, 4409 (2.5%) were Level 3, 21,232 (12.2%) were Unfunded, and 142,612 (81.7%) were not in special education. Youth assigned higher funding levels, compared to lower levels, generally had increased service use, and in the transition to adult services were more likely to use income supports, and received more income support. An important exception was youth with serious behavioural/mental health special education funding (Level 3), who had increased service use for their level of funding, but received less income support due to a reliance on Temporary versus Disability Assistance. Youth that received an accredited diploma were less likely to use income supports. Factors related to the use of income supports are further described. This study highlights differences in access to income support when youth transition to adult services and considerations around equitable access to support.

Income assistance use among young adults who were in British Columbia special education: A longitudinal cohort study

BACKGROUND

Persons with disability (PWD) experience disproportionately high poverty rates in Canada. This trend is apparent especially among youth compared to those who develop disabilities later in life. PWD in poverty have additional needs that increase barriers to full participation in society and translate to higher basic costs for daily living. Despite the existence of income assistance programs in Canada to mitigate income inequalities faced by PWDs, access to these programs can be limited.

OBJECTIVE

To describe use of income assistance for young adults with disability in British Columbia for the development of potential approaches to improve realized access to these programs.

METHODS

We conducted a population-based retrospective cohort study using British Columbia linked administrative data. We described differences in income assistance use among PWD by the level of special education funding received during primary school education (from most to least; Level 1, Level 2, Level 3, Unfunded, and no special education) and family composition. We also provided longitudinal patterns of income assistance use.

RESULTS

Of 218,324 young adults, 88% received no special education, 0.1% used Level One, 1.6% used Level Two, 2.9% used Level Three, and 7.1% used Unfunded special education coding. Young adults with Level One special education funding had the highest rates of hospitalizations and continuing care, with no hospitalization due to homelessness. Those with Level Three special education coding had higher rates of hospitalization and hospitalization due to homelessness than Level Two young adults. When transitioning to adulthood initially, Level One and Two funded individuals used relatively more disability income assistance than individuals from the other funding levels. Nearly all BCEA users with higher funded special education codes used this disability-specific program, while lesser funded special education codes used the Temporary Assistance more frequently, for a longer duration and were more likely to be persistent Temporary Assistance users.

CONCLUSIONS

Sustainable and reliable access to income assistance programs remains an issue across the heterogeneity of needs faced by young adults with disability.

Cross-ministry data on service use and limitations faced by children in special education

BACKGROUND

Children with disabilities often face limitations that cross support sectors.

OBJECTIVE

Our aim was to measure cross-ministry service use, outcomes, and functional limitations faced by children who qualified for special education.

METHODS

We used longitudinal British Columbia ministry data linked to children (0-18y) registered in K-12 education. Children were grouped by special education funding (most to least; Level 1, Level 2, Level 3, Unfunded, and no special education), and related to 1) service use patterns, 2) the age they first used disability services, and 3) functional limitations reported in health visits. We also reported how length of special education use related to disability service use.

RESULTS

Of 111,274 children, 154(0.1%) were Level 1, 4427(4.0%) Level 2, 2897(2.6%) Level 3, 13472(12.1%) Unfunded, and 90324(81.2%) not in special education. Children with higher funding levels, compared to lower levels of funding, generally were more likely to experience poorer outcomes, have functional limitations, have service needs, and receive early support. One exception was children with serious behavioural/mental health special education coding, which had poorer outcomes for their level of funding. Children received child disability supports early (about half of users started by 4y), but use was mostly limited to those with many years (9+years) of funded special education (70.7% of the all users) and biased to certain special education codes (i.e., Level 1, severe intellectual disability, and autism).

CONCLUSIONS

This study provides evidence of the long-term, diverse needs of children in special education and may be used to inform decisions surrounding their support.

Correction to 'On the beneficent thickness of water'

[This corrects the article DOI: 10.1098/rsfs.2019.0061.].

Culture and neuroscience: How Japanese and European Canadians process social context in close and acquaintance relationships

Recent cultural psychology findings suggest that social orientation affects neural social attention. Whereas independent cultures process people as separate from social context, interdependent cultures process people as dependent on social context. This research expands upon these findings, investigating what role culture plays in people's neural processing of social context for two relationship contexts, close and acquaintance relationships. To investigate, we had European Canadian and Japanese participants rate the emotions of center faces in face lineups while collecting ERP data. Lineups were either congruent, with all faces showing similar emotions, or incongruent, with center face emotions differing from background faces. To investigate relationship types, we framed face lineups to be in close or acquaintance relationships. We found that for acquaintances, only Japanese processed incongruent social context as meaningful, as seen through N400 incongruity effects. Contrasting with these patterns, only European Canadians showed N400 incongruity effects for close relationships. These patterns were seen whether or not the two groups noticed the emotional conflict, as seen by N2 incongruity effects. Finally, we found that social orientation was differentially related to the neural incongruity effects for the two relationships. These findings further elucidate the nuances of how culture affects neural social attention.

Improved method for calibration of exchange flows for a physical transport box model of Tampa Bay, FL USA

We report the results for both sequential and simultaneous calibration of exchange flows between segments of a 10-box, 1-dimensional, well mixed, bifurcated tidal mixing model for Tampa Bay. Calibrations were conducted for three model options having different mathematical expressions for evaporative loss. In approaching this project we asked three questions: does simultaneous calibration or sequential calibration yield better box model performance; which evaporation option best predicts observed salinities; and how well does model performance compare to more complex hydrodynamic models. Sequential calibration followed the classical salt balance and steady state approach. The nonlinear parameter estimator (PEST) was used for simultaneous calibration. The sequential approach proved useful in evaluating the three evaporation options. However, simultaneous calibration proved superior in predicting observed salinities but was ineffective in discerning differences between evaporation options. The simultaneously calibrated model produced residence times that fell within the range of more complex hydrodynamic models of Tampa Bay.

Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower eastern Tampa Bay

Contaminant concentrations are reported for surface water, sediment, flora and fauna collected during 2010-2011 from the mangrove fringe along eastern Tampa Bay, Florida. Concentrations of trace metals, chlorinated pesticides, atrazine, total polycyclic aromatic hydrocarbons, and polychlorinated biphenyls were species-, chemical- and location-specific. Contaminants in sediments did not exceed proposed individual sediment quality guidelines. Most sediment quality assessment quotients were less than one indicating the likelihood of no inhibitory effect based on chemical measurements alone. Faunal species typically contained more contaminants than plant species; seagrass usually contained more chemicals than mangroves. Bioconcentration factors for marine angiosperms were usually less than 10 and ranged between 1 and 31. Mercury concentrations (ppm) in blue crabs and fish did not exceed the U.S. Environmental Protection Agency fish tissue criterion of 0.3 and the U.S. Food and Drug Administration action level of 1.0. In contrast, total mercury concentrations in faunal species often exceeded guideline values for wildlife consumers of aquatic biota.

Modeling free energy availability from Hadean hydrothermal systems to the first metabolism

Off-axis Hydrothermal Systems (HSs) are seen as the possible setting for the emergence of life. As the availability of free energy is a general requirement to drive any form of metabolism, we ask here under which conditions free energy generation by geologic processes is greatest and relate these to the conditions found at off-axis HSs. To do so, we present a conceptual model in which we explicitly capture the energetics of fluid motion and its interaction with exothermic reactions to maintain a state of chemical disequilibrium. Central to the interaction is the temperature at which the exothermic reactions take place. This temperature not only sets the equilibrium constant of the chemical reactions and thereby the distance of the actual state to chemical equilibrium, but these reactions also shape the temperature gradient that drives convection and thereby the advection of reactants to the reaction sites and the removal of the products that relate to geochemical free energy generation. What this conceptual model shows is that the positive feedback between convection and the chemical kinetics that is found at HSs favors a greater rate of free energy generation than in the absence of convection. Because of the lower temperatures and because the temperature of reactions is determined more strongly by these dynamics rather than an external heat flux, the conditions found at off-axis HSs should result in the greatest rates of geochemical free energy generation. Hence, we hypothesize from these thermodynamic considerations that off-axis HSs seem most conducive for the emergence of protometabolic pathways as these provide the greatest, abiotic generation rates of chemical free energy.

Comment on "A bacterium that can grow by using arsenic instead of phosphorus"

Wolfe-Simon et al. (Research Articles, 3 June 2011, p. 1163; published online 2 December 2010) argued that the bacterial strain GFAJ-1 can vary the elemental composition of its biomolecules by substituting arsenic for phosphorus. Although their data show that GFAJ-1 is an extraordinary extremophile, consideration of arsenate redox chemistry undermines the suggestion that arsenate can replace the physiologic functions of phosphate.

Serpentinization as a source of energy at the origin of life

For life to have emerged from CO₂, rocks, and water on the early Earth, a sustained source of chemically transducible energy was essential. The serpentinization process is emerging as an increasingly likely source of that energy. Serpentinization of ultramafic crust would have continuously supplied hydrogen, methane, minor formate, and ammonia, as well as calcium and traces of acetate, molybdenum and tungsten, to off-ridge alkaline hydrothermal springs that interfaced with the metal-rich carbonic Hadean Ocean. Silica and bisulfide were also delivered to these springs where cherts and sulfides were intersected by the alkaline solutions. The proton and redox gradients so generated represent a rich source of naturally produced chemiosmotic energy, stemming from geochemistry that merely had to be tapped, rather than induced, by the earliest biochemical systems. Hydrothermal mounds accumulating at similar sites in today's oceans offer conceptual and experimental models for the chemistry germane to the emergence of life, although the ubiquity of microbial communities at such sites in addition to our oxygenated atmosphere preclude an exact analogy.

Predicted current densities in the brain during transcranial electrical stimulation

OBJECTIVE

We sought an electrical modeling approach to evaluate the potential application of finite element method (FEM) modeling to predict current pathways and intensities in the brain after transcranial electrical stimulation.

METHODS

A single coronal MRI section through the head, including motor cortex, was modeled using FEM. White matter compartments with both anatomically realistic anisotropies in resistivity and with a homogeneous resistivity were modeled. Current densities in the brain were predicted for electrode sites on the scalp and after theoretical application of a conductive head restraint device.

RESULTS

Localized current densities were predicted for the model with white matter anisotropies. Differences in predicted peak current densities were related to location of stimulation sites relative to deep sulci in the brain and scalp shunting that was predicted to increase with inter-electrode proximity. A conductive head restraint device was predicted to shunt current away from the brain when a constant current source was used.

CONCLUSIONS

The complex geometry of different tissue compartments in the head and their contrasting resistivities may jointly determine the strength and location of current densities in the brain after transcranial stimulation. This might be predictable with FEM incorporating white matter anisotropies. Conductive head restraint devices during surgery may be contraindicated with constant current stimulation.

SIGNIFICANCE

Individually optimized tcMEP monitoring and localized transcranial activation in the brain might be possible through FEM modeling.

Proving the concept of a data broker as an emergent alternative to supra-enterprise EPR systems

Electronic Patient Records systems configured into large enterprise models have become the assumed best route forward. In England, as in several other countries, this has expanded to a major meta-enterprise procurement programme. However, concerns are raised that such systems lack user ownership, and experience from other sectors shows difficulties with large enterprise systems. At a time of great change and once again shifting organizations, is this move simply building large and ponderous edifices with unstable materials? Latest software engineering research is now demonstrating the potential of an alternative model, enabling trusted information brokers to search out in real time at point of use data held in registered local and departmental systems. If successful, this could enable a new and less cumbersome paradigm. The data could move where needed whatever the service configuration. A concept demonstrator has been built set in the context of health and social care in England. It is important for all technological support to the health sector to be reviewed as new technologies emerge so as to identify and exploit new opportunities, and the results of this 3 year project show that the health record information broker route merits further investigative research.

Improved Prediction of Fatal Myocardial Infarction Using the Ankle Brachial Index in Addition to Conventional Risk Factors

Background— Prediction of major cardiovascular and cerebrovascular events using conventional risk factor models is limited. Noninvasive measures of subclinical atherosclerosis such as the ankle brachial index (ABI) could improve risk prediction and provide more focused primary prevention strategies. We wished to determine the added value of a low ABI in the prediction of long-term risk of cardiovascular and cerebrovascular events and death.

Methods and Results— In 1988, 1592 men and women 55 to 74 years of age were randomly selected from the age-sex registers of 11 general practices in Edinburgh, Scotland, and followed up over a period of 12 years for incident events. After adjustment for age and sex, an ABI ≤0.9 was predictive of an increased risk of fatal myocardial infarction (MI), cardiovascular death, all-cause death, combined fatal and nonfatal MI, and total cardiovascular events. After further adjustment for prevalent cardiovascular disease, diabetes, and conventional risk factors, a low ABI was independently predictive of the risk of fatal MI. Addition of the ABI significantly ( P ≤0.01) increased the predictive value of the model for fatal MI compared with a model containing risk factors alone. Comparison of areas under receiver operator characteristic curves confirmed that a model including the ABI discriminated marginally better than one without.

Conclusions— Addition of the ABI significantly improved prediction of fatal MI over and above that of conventional risk factors. We recommend that the ABI be incorporated into routine cardiovascular screening and that the potential of its inclusion into cardiovascular scoring systems (with a view to improving their accuracy) now be examined.

Intracellular and extracellular calcium utilization during hypoxic vasoconstriction of cyclostome aortas

Hypoxic vasoconstriction (HV) is an intrinsic response of mammalian pulmonary and cyclostome aortic vascular smooth muscle. The present study examined the utilization of calcium during HV in dorsal aortas (DA) from sea lamprey and New Zealand hagfish. HV was temporally correlated with increased free cytosolic calcium (Ca2+c) in lamprey DA. Extracellular calcium (Ca2+o) did not contribute significantly to HV in lamprey DA, but it accounted for 38.1 +/- 5.3% of HV in hagfish DA. Treatment of lamprey DA with ionomycin, ryanodine, or caffeine added to thapsigargin-reduced HV, whereas HV was augmented by BAY K 8644. Methoxyverapamil (D600) in zero Ca2+o did not affect HV in lamprey DA, nor did it prevent further constriction when Ca2+o was restored during hypoxia in hagfish DA. Removal of extracellular sodium (Na+o) caused a constriction in both species. Lamprey DA relaxed to prehypoxic tension following return to normoxia in zero Na+o, whereas relaxation was inhibited in hagfish DA. Relaxation following HV was inhibited in lamprey DA when Na+o and Ca2+o were removed. These results show that HV is correlated with [Ca2+]c in lamprey DA and that Na+/Ca2+ exchange is used during HV in hagfish but not lamprey DA. Multiple receptor types appear to mediate stored intracellular calcium release in lamprey DA, and L-type calcium channels do not contribute significantly to constriction in either cyclostome.

Blood and extracellular fluid volume in whole body and tissues of the Pacific hagfish, Eptatretus stouti

Whole-body and 20 individual-tissue (51)Cr-RBC (red cell space; RCS) and (99)Tc-diethylenetriaminepentaacetic acid (extracellular space; ECS) spaces were measured in seven unanesthetized Pacific hagfish (Eptatretus stouti). Volume indicators were administered via a dorsal aortic cannula implanted the previous day. Blood samples were collected at 6, 12, 18, and 24 h after injection. Tissues were removed at 24 h and radioactivity was measured; tissue water content (percent of wet weight) was determined by desiccation at 95 degrees C for 48 h. Mixing rates of both indicators were identical and were essentially complete by 12 h, indicating that blood convection is the rate-limiting process. At 24 h, the whole-body RCS was 19.3+/-2.1 mL kg(-1) body weight, and the ECS was 338.5+/-15.2 mL kg(-1) body weight. Blood volume estimated from the 24-h RCS and the mean central hematocrit (14%) was 137.9 mL kg(-1) body weight. Liver RCS (118.6+/-30.5 microL g(-1) tissue weight) was twice that of any other tissue and was also the most variable, ranging from 59 to 263 microL g(-1), whereas liver ECS (406.0+/-34.3 microL g(-1)) was in the range of other tissues, and water content (66.9%+/-3.5%) was low. Gill RCS (55.9+/-5.7 microL g(-1)), ECS (415.3+/-37.7 microL g(-1)), and percent water (83.1%+/-0.8%) were higher than most other tissues. RCS, ECS, and percent water were consistently lowest in ovum (1.1+/-0.02 microL g(-1), 111.1+/-4.3 microL g(-1), 51.3%+/-3.5%, respectively). Tongue, notocord, and myotome had generally lower RCS (2.1+/-0.4, 2.2+/-0.5, 7.1+/-0.1 microL g(-1), respectively) and ECS (121.2+/-7.0, 246.3+/-17.4, 185.3+/-16.7 microL g(-1), respectively), although their water content was in the midrange (74.7+/-0.5, 81.2+/-1.6, 74.4%+/-0.6%, respectively). Skin had a low RCS (6.8+/-1.1) and midrange ECS (387.5+/-28.0) but very low water content (61.2%+/-2.1%). These findings confirm that hagfish blood volume is at least twice as large as other fish, whereas our estimate of extracellular fluid volume is larger than previously reported and more in line with the predicted interstitial volume. RCS, ECS, and water content vary, often independently, between tissues, which may perhaps be indicative of specific tissue needs or functions. A distinct spleen is lacking in hagfish, and the liver appears to serve this function by sequestering red cells. To our knowledge, this is the first report of tissue ECS in Myxiniformes.

Effects of hypoxia on isolated vessels and perfused gills of rainbow trout

Local hypoxia dilates systemic and constricts pulmonary blood vessels in mammals without neural or humoral involvement. The direct effects of hypoxia on isolated vessels from bony fish have not been examined. In the present study, isolated vessels (efferent branchial artery, EBA; coeliacomesenteric artery, CMA; ventral aorta, VA; and anterior cardinal vein, ACV) from rainbow or steelhead trout (Oncorhynchus mykiss) were subjected to either passive load (resting tension) or contracted with a ligand or 50 mM KCl and then subjected to 60 min of hypoxia by N(2) administration and an additional 30 min of normoxia. All vessels were usually refractory to hypoxia under conditions of resting tension. EBAs, CMAs and VAs pre-contracted with a receptor-mediated ligand were all significantly relaxed by hypoxia and only VAs recovered significantly upon subsequent restoration of normoxia. In contrast, tension in all arteries pre-contracted with 50 mM KCl was elevated further in response to hypoxia. Conversely, ligand-contracted ACVs responded to hypoxia with a further increase in tension, whereas KCl-contracted ACVs relaxed. During apparently random 2-3-week periods EBA and CMA from steelhead and EBA from rainbow trout were hyper-reactive to hypoxia. Steelhead vessels responded to hypoxia with a rapid contraction that increased in magnitude over 3 days. These contractions were independent of pre-stimulation and they were dose-dependent upon PO(2). In isolated gills, hypoxic perfusate produced an immediate but transient elevation of resistance (R(GILL)) in all four gill arches. R(GILL) increased by as much as 30% of initial values and this response was unaltered upon a second hypoxic exposure. These studies demonstrate that isolated vascular segments of rainbow trout are indeed responsive to hypoxia and that these differential responses are vessel and tone dependent and the overall response may be altered by as yet unknown seasonal or environmental factors. Hypoxia-induced arterial relaxation is blocked by elevated external [K(+)], implicating alteration of transmembrane K(+) conductance and/or membrane potential in this depressor response. K(+)-channel closure or voltage-gated Ca(2+) influx cannot account for arterial vasoconstriction due to hypoxia during KCl contractions. Vascular responses to hypoxia could have a profound impact on local flow in vivo and could mediate ventilation-perfusion matching in the branchial circulation of fish.

Increased facial temperature as an early warning in Sudden Infant Death Syndrome

The promotion of supine sleeping position in young infants has resulted in significant declines in the incidence of Sudden Infant Death Syndrome although little is understood in terms of mechanisms. We hypothesize that supine sleeping position promotes appropriate thermal regulation via the face and head which is the major source of infant heat loss. By facilitating temperature regulation, the supine position ensures that the centre for thermoregulation in the hypothalamus does not become dysfunctional due to local temperature fluctuations. Because these hypothalamic, thermoregulatory neurones are synaptically linked to those regulating respiration in the medulla, adequate temperature control by the infant maintains normal respiration. In contrast, an increase in face and head temperature over and above core temperature would suggest thermoregulatory stress and an increased likelihood of respiratory apnoea.

Hypoxic vasoconstriction of cyclostome systemic vessels: the antecedent of hypoxic pulmonary vasoconstriction?

Hypoxic vasoconstriction (HV) is an intrinsic response of mammalian pulmonary vascular smooth muscle (VSM). In the present study, HV was examined by myography of vessel rings from three primitive vertebrates: New Zealand hagfish (NZH), Pacific hagfish (PH), and sea lamprey (SL). Hypoxia dilated pre-gill arteries (ventral aorta, afferent branchial) from all species, whereas it contracted systemic arteries [dorsal aorta (DA), efferent branchial, celiacomesenteric]. DA HV was reproducible over several days, and it could be sustained in NZH for 8 h without adverse effects. Tension was proportional to PO(2), and half-maximal HV was obtained at PO(2) (mmHg) of 4.7 +/- 0. 2 (NZH), 0.8 +/- 0.1 (PH), and 10.7 +/- 1.9 (SL). HV did not require preconditioning (preexisting contractile stimulus) and was unaffected by elevated extracellular potassium (200 mM NZH; 80 mM SL); removal of the endothelium (NZH); or inhibitors of cyclooxygenase, lipoxygenase, cytochrome P-450 or antagonists of alpha-adrenergic, muscarinic, nicotinic, purinergic, or serotoninergic receptors. These results show that HV is an intrinsic feature of systemic VSM in cyclostomes and suggest that HV has been in the repertoire of VSM responses, since the origin of vertebrates. The exceptionally hardy HV in cyclostome DA may provide a useful model with which to examine both the phylogeny and mechanisms of this response.

Angiotensin signaling and receptor types in teleost fish

Despite advances characterizing mammalian angiotensin receptors, the phylogeny of fish angiotensin receptors remains unclear. Three aspects of receptor function: (1) the nature of the ligand; (2) the second messenger system activated by it; and (3) the pharmacological profile of specific antagonists, are examined to provide insight into the fish receptor. (1) The octapeptide sequences of fish and mammalian angiotensin II (ANG II) are nearly homologous, differing only at the first and fifth residues. Both peptides are almost equally efficacious and equipotent in heterologous systems and both contain key agonist switches Tyr(4) and Phe(8) necessary to activate mammalian AT(1)-type receptors. (2) ANG II increases inositol trisphosphate production, and elevates intracellular calcium in fish tissues consistent with activation of the AT(1) receptor. (3) However, the specific mammalian sartan-type AT(1) antagonists, e.g. losartan, produce inconsistent results in fish often acting as partial agonists, or inhibiting only at elevated concentrations. Because sartans and ANG II act at distinct sites on the AT(1) receptor, we propose that the teleost receptor is an AT(1)-type receptor that is fairly well conserved with respect to both the ANG binding site and coupling to the second messenger system, whereas the sartan binding site has been poorly conserved. The evidence for non-AT(1) type ANG II receptors in teleosts is limited. Mammalian AT(2) receptor antagonists are generally ineffective but may block at elevated, non-specific doses. Truncated ANG II fragments, ANG III and ANG IV, are often less potent than ANG II, however, their receptors have not been examined. Preliminary studies in trout indicate that angiotensin 1-7 may have a mild vasodilatory effect; additional work is needed to determine if non-AT(1)-type receptors are involved.

Structure-apoptotic potency evaluations of novel sterols using human leukemic cells

Three oxidized analogs of cholesterol have been characterized for their ability to cause apoptotic cell death in CEM-C7-14 human leukemic cells. In addition to testing 15-ketocholestenol (K15), 15-ketocholestenol hydroxyethyl ether (CK15), and 7-ketocholesterol hydroxyethyl ether (CK7), an oxysterol of known apoptotic response, 25-hydroxycholesterol (25OHC), served as a standard for comparison. Growth studies based on dye exclusion by viable cells while using a sublethal concentration of oxysterols ranked their potency for cell kill as 25OHC > K15 > CK15 > CK7. Both the TUNEL assay (terminal deoxynucleotidyl transferase-mediated dUTP-X nick end labeling), which quantifies the amount of DNA nicks caused by a toxic agent, and the MTT assay, which measures cell metabolism and thus reflects cell viability, substantiated the same rank order. An ELISA assay for evaluating release of DNA fragments into the cytosol after treatment gave a similar potency order. The oncogene c-myc mRNA was suppressed by all three oxysterols, with 25OHC and K15 being the most potent suppressors. Hoechst and Annexin V staining documented that these oxysterols kill cells by an apoptotic pathway as evidenced by condensation of nuclear chromatin and plasma membrane inversion, respectively. From these in vitro studies, we believe that 25OHC, K15, and possibly CK15 have the potential to be chemotherapeutic agents.

Purification, structural characterization, and myotropic activity of endothelin from trout, Oncorhynchus mykiss

Endothelin (ET) from a nontetrapod species has never been characterized, either structurally or biologically. A single molecular form of trout ET with 21-amino-acid residues was isolated in pure form from an extract of the kidney of the steelhead trout, Oncorhynchus mykiss and its primary structure established as Cys-Ser-Cys-Ala-Thr-Phe-Leu-Asp-Lys-Glu10-Cys-Val-Tyr-Phe-Cys-His- L eu-Asp-Ile-Ile20-Trp. This amino acid sequence shows only three substitutions (Ala4-->Ser, Thr5-->Ser, and Phe6-->Trp) compared with human ET-2, demonstrating that the structure of the peptide has been well conserved during evolution and that the pathway of posttranslational processing of preproendothelin in the trout is probably similar to that in mammals. Synthetic trout ET produced concentration-dependent constrictions of isolated rings of vascular tissue from trout efferent branchial artery (EBA; pD2 = 7. 90 +/- 0.06, n = 5), caeliacomesenteric artery (pD2 = 8.03 +/- 0. 04, n = 4), anterior cardinal vein (ACV; pD2 = 8.57 +/- 0.25, n = 4), and rat abdominal aorta (AO; pD2 = 8.86 +/- 0.08, n = 7). Trout and rat vessels were more sensitive to mammalian ET-1 than to trout ET (pD(2) for human ET-1 in: EBA = 9.12 +/- 0.14; ACV = 9.90 +/- 0.15; AO = 8.86 +/- 0.08), but there was no significant difference in the maximum tension produced by either peptide in these vessels.

Application of risk analysis and geographic information system technologies to the prevention of diarrheal diseases in Nigeria

Among the poor in developing countries, up to 20% of an infant's life experience may include diarrhea. This problem is spatially related to the lack of potable water at different sites. This project used risk analysis (RA) methods and geographic information system (GIS) technologies to evaluate the health impact of water source. Maps of Imo State, Nigeria were converted into digital form using ARC/INFO GIS software, and the resulting coverages included geology, hydrology, towns, and villages. A total of 11,537 diarrheal cases were reported. Thirty-nine water sources were evaluated. A computer modeling approach called probabilistic layer analysis (PLA) spatially displayed the water source at layers of geology, hydrology, population, environmental pollution, and electricity according to a color-coded five-point ranking. The water sources were categorized into A, B, and C based on the cumulative scores < 10 for A, 10-19 for B, and > 19 for C. T-test showed revealed significant differences in diarrheal disease incidence between categories A, B, and C with mean +/- SEM values of 1.612 +/- 0.325, 6.257 +/- 0.408, and 15.608 +/- 2.151, respectively. The differences were significant between categories A and B (P = 0.0000022), A and C (P = 0.0000188), and B and C (P = 0.0011348). The PLA enabled estimation of the probability of the risk of diarrheal diseases occurring at each layer and solutions to eliminate these risks.

Gestational magnesium deficiency is deleterious to fetal outcome

A number of recent epidemiological findings have implicated magnesium as being essential to fetal well-being. Few studies, however, have examined the relationship between maternal requirements for dietary magnesium and subsequent mortality and morbidity in offspring. The present study uses a rodent model of dietary-induced hypomagnesemia to investigate the effects of magnesium deficiency prior to and during gestation on neonatal morbidity and mortality. Magnesium deficiency during gestation significantly increased neonatal mortality and morbidity. Such increases were associated with a reduced free magnesium concentration in both maternal and offspring blood and an increased incidence of periventricular hemorrhage and edema in newborn pups as observed by magnetic resonance imaging and histology. Animals fed a magnesium-deficient diet before mating but given magnesium supplementation during gestation did not demonstrate a significant change in neonatal mortality and morbidity when compared to control animals. The significant improvement in fetal outcome with dietary magnesium supports the concept of magnesium supplementation during pregnancy.

N-terminal heterogeneity of parenchymal and cerebrovascular Abeta deposits

The goals of this study were twofold: to determine whether species differences in Abeta N-terminal heterogeneity explain the absence of neuritic plaques in the aged dog and aged bear in contrast to the human; and to compare Abeta N-terminal isoforms in parenchymal vs cerebrovascular Abeta (CVA) deposits in each of the species, and in individuals with Alzheimer disease (AD) vs nondemented individuals. N-terminal heterogeneity can affect the aggregation, toxicity, and stability of Abeta. The human, polar bear, and dog brain share an identical Abeta amino acid sequence. Tissues were immunostained using affinity-purified polyclonal antibodies specific for the L-aspartate residue of Abeta at position one (AbetaN1[D]), D-aspartate at N1 (AbetaN1[rD]), and pyroglutamate at N3 (AbetaN3[pE]) and p3, a peptide beginning with leucine at N17 (AbetaN17[L]). The results demonstrate that each Abeta N-terminal isoform can be present in diffuse plaques and CVA deposits in AD brain, nondemented human, and the examined aged animal models. Though each Abeta N-terminal isoform was present in diffuse plaques, the average amyloid burden of each isoform was highest in AD vs polar bear and dog (beagle) brain. Moreover, the ratio of AbetaN3(pE) (an isoform that is resistant to degradation by most aminopeptidases) vs AbetaN17(L)-x (the potentially nonamyloidogenic p3 fragment) was greatest in the human brain when compared with aged dog or polar bear. Neuritic plaques in AD brain typically immunostained with antibodies against AbetaN1(D) and AbetaN3(pE), but not AbetaN17(L) or AbetaN1(rD). Neuritic deposits in nondemented individuals with atherosclerotic and vascular hypertensive changes could be identified with AbetaN1(D), AbetaN3(pE), and AbetaN1(rD). The presence of AbetaN1(rD) in neuritic plaques in nondemented individuals with atherosclerosis or hypertension, but not in AD, suggests a different evolution of the plaques in the two conditions. AbetaN1(rD) was usually absent in human CVA, except in AD cases with atherosclerotic and vascular hypertensive changes. Together, the results demonstrate that diffuse plaques, neuritic plaques, and CVA deposits are each associated with distinct profiles of Abeta N-terminal isoforms.

The emergence of life from iron monosulphide bubbles at a submarine hydrothermal redox and pH front

Here we argue that life emerged on Earth from a redox and pH front at c. 4.2 Ga. This front occurred where hot (c. 150 degrees C), extremely reduced, alkaline, bisulphide-bearing, submarine seepage waters interfaced with the acid, warm (c. 90 degrees C), iron-hearing Hadean ocean. The low pH of the ocean was imparted by the ten bars of CO2 considered to dominate the Hadean atmosphere/hydrosphere. Disequilibrium between the two solutions was maintained by the spontaneous precipitation of a colloidal FeS membrane. Iron monosulphide bubbles comprising this membrane were inflated by the hydrothermal solution upon sulphide mounds at the seepage sites. Our hypothesis is that the FeS membrane, laced with nickel, acted as a semipermeable catalytic boundary between the two fluids, encouraging synthesis of organic anions by hydrogenation and carboxylation of hydrothermal organic primers. The ocean provided carbonate, phosphate, iron, nickel and protons; the hydrothermal solution was the source of ammonia, acetate, HS-, H2 and tungsten, as well as minor concentrations of organic sulphides and perhaps cyanide and acetaldehyde. The mean redox potential (delta Eh) across the membrane, with the energy to drive synthesis, would have approximated to 300 millivolts. The generation of organic anions would have led to an increase in osmotic pressure within the FeS bubbles. Thus osmotic pressure could take over from hydraulic pressure as the driving force for distension, budding and reproduction of the bubbles. Condensation of the organic molecules to polymers, particularly organic sulphides, was driven by pyrophosphate hydrolysis. Regeneration of pyrophosphate from the monophosphate in the membrane was facilitated by protons contributed from the Hadean ocean. This was the first use by a metabolizing system of protonmotive force (driven by natural delta pH) which also would have amounted to c. 300 millivolts. Protonmotive force is the universal energy transduction mechanism of life. Taken together with the redox potential across the membrane, the total electrochemical and chemical energy available for protometabolism amounted to a continuous supply at more than half a volt. The role of the iron sulphide membrane in keeping the two solutions separated was appropriated by the newly synthesized organic sulphide polymers. This organic take-over of the membrane material led to the miniaturization of the metabolizing system. Information systems to govern replication could have developed penecontemporaneously in this same milieu. But iron, sulphur and phosphate, inorganic components of earliest life, continued to be involved in metabolism.

Matrix metalloproteinases in dog brains exhibiting Alzheimer-like characteristics

We have previously reported that the amount of the neuronal matrix metalloproteinase (MMP) MMP-9, capable of cleaving beta-amyloid,-40 predominantly at Leu34-Met35, is increased in a latent form in hippocampal specimens from AD patients and have suggested that the lack of activation of this enzyme may contribute to the deposition of beta-amyloid in plaques. The current study addresses whether similar matrix proteinases are detectable in amyloid-positive and -negative brain specimens of aged beagles. Using quantitative zymography, three major neutral proteinases with molecular masses of 60, 95, and 280 kDa were readily detected. These enzymes have the characteristics of MMPs because they were inhibited by EDTA and 1, 10-phenanthroline, and their activities were restored by addition of both Ca2+ and Zn2+. The 95- and 280-kDa proteinases cross-reacted with specific monoclonal antibodies to human MMP-9 (gelatinase B; EC 3.4. 24.35). Canine MMP-9 was latent because activation by organomercurial treatment resulted in a characteristic decrease in molecular mass. Statistical analysis revealed no difference in the 60-kDa proteinase activity in amyloid-positive and -negative brain specimens. However, significantly increased amounts of latent MMP-9 were observed in amyloid-positive brain specimens (p < or = 0.05) compared with amyloid-negative brain specimens. The observations document that changes in MMP-9 expression in amyloid-positive beagle brains are similar to those reported in the human Alzheimer's disease hippocampus and suggest the possibility that insufficient activation of MMP-9 may contribute to beta-amyloid accumulation, a hypothesis that needs to be further investigated.

Distribution of beta-amyloid in the canine brain

The distribution of amyloid-beta protein (A beta) in the canine brain was demonstrated by immunochemistry on serially sectioned tissues from 10 aged mixed breed dogs. Summation of quantitative data and relegation to anatomical sites for the 10 dogs showed A beta to be widely distributed in the cortex and hippocampus while completely absent in the brain stem and cerebellum. The highest density of A beta was in the dentate gyrus of the hippocampus. Cortical areas exhibiting the greatest A beta deposition were the posterior and medial suprasylvius gyrus and the proreus gyrus of the frontal lobe. Unlike humans the canine entorhinal cortex, amygdala, basal ganglia and olfactory bulbs were rarely affected. This suggested that the highly developed olfactory pathways of the canine are generally spared from A beta deposition.

Age-specific onset of beta-amyloid in beagle brains

As part of an effort to characterize Alzheimer's disease-like neuropathy in the canine brain we have determined the age of onset of spontaneous beta-amyloid deposition in 103 laboratory-raised beagles. Tissue samples for each subject were obtained from hippocampal and cortical regions and examined for the incidence and density of beta-amyloid deposition after staining with modified Bielschowsky silver stain and immunohistochemistry. Amyloid deposition was characterized as diffuse plaque or cloud-like formation. The diffuse type of beta-amyloid plaque formation predominated in all brain regions examined. A threshold effect of plaque development was observed; no plaques were apparent in dogs before the age of 10 years, while 36% of dogs aged 11.1-12.9, 60% of dogs aged 13.0-15.0, and 73% of dogs aged 15.1-17.8 developed beta-amyloid deposits. Additionally, a significant increase in plaque density was observed with increasing age.

Carboxy terminal of beta-amyloid deposits in aged human, canine, and polar bear brains

Immunocytochemistry, using antibodies specific for different carboxy termini of beta-amyloid. A beta 40 and A beta 42(43), was used to compare beta-amyloid deposits in aged animal models to nondemented and demented Alzheimer's disease human cases. Aged beagle dogs exhibit diffuse plaques in the absence of neurofibrillary pathology and the aged polar bear brains contain diffuse plaques and PHF-1-positive neurofibrillary tangles. The brains of nondemented human subjects displayed abundant diffuse plaques, whereas the AD cases had both diffuse and mature (cored) neuritic plaques. Diffuse plaques were positively immunostained with an antibody against A beta 42(43) in all examined species, whereas A beta 40 immunopositive mature plaques were observed only in the human brain. Anti-A beta 40 strongly immunolabeled cerebrovascular beta-amyloid deposits in each of the species examined, although some deposits in the polar bear brain were preferentially labeled with anti-A beta 42(43). beta-amyloid deposition was evident in the outer molecular layer of the dentate gyrus in the aged dog, polar bear, and human. Within this layer, A beta 42 was present as diffuse deposits, although these deposits were morphologically distinct in each of the examined animal models. In dogs, A beta 42 was cloud-like in nature; the polar bear demonstrated a more aggregated type of deposition, and the nondemented human displayed well-defined deposits. Alzheimer's disease cases were most frequently marked by neuritic plaques in this region. Taken together, the data indicate that beta-amyloid deposition in aged mammals is similar to the earliest stages observed in human brain. In each species, A beta 42(43) is the initially deposited isoform in diffuse plaques.

Pharmacological properties of the cloned alpha 1A/D-adrenoceptor subtype are consistent with the alpha 1A-adrenoceptor characterized in rat cerebral cortex and vas deferens

1. The pharmacological characteristics of cloned mammalian alpha 1A/D-, alpha 1B- and alpha 1C-adrenoceptor subtypes expressed in rat 1 fibroblasts were determined in comparison to the binding and functional properties of these subtypes in rat tissues. 2. Analysis of [3H]-prazosin binding to membrane homogenates from rat 1 fibroblast cells expressing each of the alpha 1-subtypes indicated high affinity binding to a single population of binding sites. Binding affinities were similar for alpha 1A/D-, alpha 1B- and alpha 1C-subtypes (Kds: 0.13, 0.10 and 0.15 nM respectively) although a higher density of alpha 1B- and alpha 1C-receptors (Bmax: 4068 and 10,323 fmol mg-1 protein respectively) were expressed in comparison to alpha 1A/D (838 fmol mg-1). 3. Displacement of [3H]-prazosin from membranes expressing cloned alpha 1-adrenoceptor subtypes revealed that 5-methyl-urapidil, WB 4101, benoxathian and phentolamine displayed high affinity and selectivity for alpha 1A/D- over alpha 1B-subtypes. These compounds also had high affinity and selectivity for alpha 1C- over alpha 1B-subtypes. 5-Methyl-urapidil showed selectivity for alpha 1C (Ki 0.60 +/- 0.16 nM) over both alpha 1A/D (Ki, 9.8 +/- 2.8 nM) and alpha 1B (Ki 57.2 +/- 12 nM) subtypes. Prazosin and doxazosin were not subtype selective. 4. In comparison to [3H]-prazosin a similar pharmacological profile was obtained with [125I]-HEAT using cloned alpha 1A/D-, alpha 1B- and alpha 1C-adrenoceptors expressed in rat 1 fibroblasts. 5. The affinities of prazosin, WB 4101, 5-methyl-urapidil, phentolamine and benoxathian at cloned alpha 1A/D-receptors were consistent with alpha 1A affinities determined with chlorethylclonidine-treated rat cortical membranes. Affinities at cloned XIB-receptors were consistent with alpha 1B affinities determined with rat liver membranes.6. Using the epididymal rat vas deferens as a functional measure of alpha 1A affinity, prazosin (pA29.23 +/- 0.28), WB 4101 (pA2 9.58 +/- 0.12), phentolamine (pKB 7.90 +/- 0.16), benoxathian (pKB 9.21 +/- 0.21)and 5-methyl-urapadil (pKB 8.51 +/-0.16) were potent antagonists of noradrenaline-induced contractions.7. At present, evidence from cloning studies suggests the existence of at least three alpha 1-adrenoceptor subtypes. In contrast to the recent proposal for alpha l-adrenoceptor classification, the pharmacology of the cloned alpha 1A/D (or alpha lD)-adrenoceptor is more consistent with that of an alpha 1A-adrenoceptor characterized in rat cerebral cortex and vas deferens.

Hydrothermal and oceanic pH conditions of possible relevance to the origin of life

Because of the continuous focusing of thermal and chemical energy, ancient submarine hot springs are contenders as sites for the origin of life. But it is generally assumed that these would be of the acid and high-temperature 'black smoker' variety (Corliss et al., 1981). In fact today the greater part of the ocean circulates through off-ridge springs where it issues after modification at temperatures of around 40 degrees C or so but with the potential to reach 200 degrees C. Such offridge or ridge-flank springs remind us that there are other candidate sites for the origin of life. Although there is no firm indication of the pH of these off-ridge springs we have argued that the solutions are likely to be alkaline rather than acid, We test the feasibility of this idea using EQ geochemical water-rock interaction modelling codes (Wolery 1983) and find that for a range of possible initial chemistries of Hadean seawater, the pH of issuing solutions at around 200 degrees C is around one or more units alkaline. Such pH values hold for interaction with both basaltic and komatiitic crust. The robustness of this result suggests to us that alkaline submarine springs of moderate temperature, carrying many hundreds of ppm HS to the ocean basins, are also serious contenders as sites for the origin of life, particularly as Hadean seawater was probably slightly acid, with a dissolved iron concentration approaching 100 ppm. On mixing of these solutions, supersaturation, especially of iron sulphide, would lead to the precipitation of colloidal gels. In our view iron sulphide was the likely substance of, or contributor to, the first vesicle membranes which led to life, as the supply organic molecules would have been limited in the Hadean. Such a membrane would have bid catalytic properties, expansivity, and would have maintained the natural chemiosmotic gradient, a consequence of the acid ocean and the alkaline interior to the vesicles.

[FeS/FeS2], a redox system for the origin of life (some experiments on the pyrite-hypothesis)

The FeS/FeS, redox system, whose importance is stressed in recent theories on the origin of life, has been tested experimentally. In this paper it is demonstrated by thermodynamical calculations as well as by experiments, that cyclohexanone, which served as model compound, can be reduced by the aforementioned redox system. Reactions were carried out in methanol and DMF at 25 degrees C and at 100 degrees C. Besides products that were synthesised in both solvents, like cyclohexanethiol and dicyclohexydisulphide, special compounds were obtained in methanol and in DMF, because of the involvement of the respective solvent in the reaction. Yields of reduced compounds were lower in methanol owing to compound that hindered the reduction (cyclohexylketal). With increasing temperature and duration the amount of reduced compounds increased. Further experiments have shown that 1,1-cyclohexanedithiol is likely to be a necessary intermediate for the reduced products. The experiments give evidence to the 'pyrite hypothesis', which postulates that the FeS/FeS2, redox system was of importance for the origin of life.

Beta-amyloid accumulation in aged canine brain: a model of early plaque formation in Alzheimer's disease

We characterized eight aged beagles (maintained from birth in a laboratory colony) and one black Labrador using Bielschowsky's, thioflavine S, and Congo red staining, and antibodies to the beta-amyloid peptide, dystrophic neurites, and other plaque components. All plaques within these canine brains were of the diffuse subtype and were neither thioflavine S- nor Congo red-positive. The majority of plaques in the entorhinal cortex contained numerous neurons within them while plaques in the dentate gyrus did not. beta-Amyloid immunoreactivity was also present within select neurons and neuronal processes and was detected as a diffuse linear zone corresponding to the terminal fields of the perforant path. There was no significant correlation between extent of beta-amyloid accumulation and neuron number in entorhinal cortex. Neither tau-1, PHF-1, nor SMI-31-immunostaining revealed dystrophic fibers, confirming the classification of these plaques as diffuse. Canine plaques did not appear to contain bFGF- or HS-positive immunostaining. This may explain why neuritic involvement was not detected within these canine plaques. It is possible that the beta-amyloid within the canine brain has a unique primary structure or may not be in an assembly state that adversely affects neurons.

Perineuronal satellitosis in the human hippocampal formation

A previously unreported example of perineuronal satellitosis in the medial CA1 and adjacent subiculum in the human hippocampal formation is described. This phenomenon is characterized by a clustering of glial cells in relation to the perikarya of a subpopulation of neurons in the deep pyramidal layer and around most neurons scattered in the stratum oriens and subcortical white matter. Most of the perineuronal satellite glia were identified as oligodendrocytes based on their nuclear chromatin patterns and antigenic properties. Satellite oligodendrocytes were mostly of the medium dense variety. A type of satellite glia with nuclear features of the dark oligodendrocyte could not be identified unequivocally using the antigenic criteria employed in this study.

Life span changes in the verbal categorization of odors

An odor description task was used to explore age-related change in odor perception based on 1.19 million U.S. and Canadian respondents (ages 10-90 years) to the National Geographic Smell Survey. Respondents sampled six microencapsulated odorants and selected 1 of 11 descriptors to characterize each smell. Four odors were characterized by strong consensus endorsement of a single descriptor. This consensus weakened with advancing age, and nonmodal descriptors were endorsed more frequently. Nonmodal responses were neither randomly selected, nor systematically biased across odors. Rather, they showed odor-specific patterns of change. Together, these results suggest a marked change in odor categorization across the life span. Odor descriptor profiles were used to generate age-specific multidimensional scaling maps. Stimulus configurations were stable from the third through fifth decades. Those from the sixth through ninth decades showed major displacements for two odors, and suggest that the sweet dimension of odor quality may be particularly variable with maturation.

Familial influence on plaque formation in the beagle brain

Aged canines exhibit central neuropathological changes strikingly similar to those seen in patients with Alzheimer's disease. In this study, brain tissue from pure bred beagles raised in a controlled environment were examined for Alzheimer-like pathology. The mean age of the animals was 15.6 years. The incidence of plaques among these 29 dogs was 65.5%. Of the 19 samples that demonstrated Alzheimer-like pathology, 18 were characterized as diffuse and one as neuritic. Plaque density was found to be independent of age. Plaque numbers were highest in the perirhinal cortex and the adjacent temporal cortex. Familial influence on plaque development is supported by congruence within 15 of the 16 litters examined (p < 0.001). In this environmentally controlled group the diffuse plaques were rarely converted to the dense neuritic plaques found in Alzheimer's disease.

Long-term survival of neural transplants to senescence in rats

A critical issue for clinical and research applications of transplant techniques is the long-term survival of transplanted tissue and its effect on the host brain. In this study, entorhinal cortices from donor embryos were transplanted into the lesioned angular bundle of juvenile male Sprague-Dawley rats. Animals were maintained for 2 years and then sacrificed for histological and histochemical examinations. The results indicate that entorhinal transplants survive to old age and that both the host and transplant tissues maintain morphological features consistent with those of short-term neural grafts. An unexpected finding of this experiment was the persistence in the transplanted tissue and adjacent host cortex of a pattern of AChE staining which is typical of early postnatal development.

An autoimmune aetiology for hypothyroidism following interferon therapy for breast cancer

Alpha-interferon has been administered as an adjuvant treatment for women with loco-regional relapse of breast cancer. During the course of treatment 5/10 (50%) of women receiving interferon developed de novo thyroid autoantibodies. Three patients became clinically myxoedematous, with biochemical evidence of hypothyroidism which responded to thyroxine replacement therapy. The leucocyte alpha-interferon preparations used in the trial enhanced Class I but not Class II MHC antigens on thyrocytes in vitro. These data strongly suggest that patients receiving alpha-interferon therapy should be closely monitored for the possible development of thyroid dysfunction and that thyroid antibody determination can greatly help to predict overt thyroid clinical abnormalities.

Advances in platinum cancer chemotherapy. Advances in the design of cisplatin analogues

In the past 4 years substantial progress has been made in the development of platinum cancer chemotherapy. A number of drug candidates have undergone clinical trials and one 'second generation' platinum drug, carboplatin, has been approved for use in the treatment of ovarian and small cell lung cancer. This review covers the major developments since the last international conference on Platinum Chemotherapy in Vermont, and attempts to highlight the primary factors that appear to be influencing the synthesis and screening of potential third generation platinum drugs. A predominant feature in the evaluation of analogues has been the emphasis on chelating diamine complexes, in particular those of diaminocyclohexane, which show activity in L1210 tumours that are resistant to cisplatin, and the use of a wide range of carboxylate ligands as a means of circumventing solubility and toxicity problems inherent in the parent compounds. There has also been an increased effort in studies relating to complexes containing mixed amines and functionalised amines, building on the assumption, which remains valid to date, that two amines are a necessary requirement for anti-tumour activity. Efforts have also been made to address the use of complexes containing biologically active ligands, and the concept of targeting compounds to specific organs and formulating drugs to achieve more specific activity or controlled release of drugs with lower toxicities. These may provide a viable route to drugs that can be administered more easily, for example by an oral route, or show a different spectrum of activity. However, it may prove difficult to adequately characterise these more complex systems. The major problem encountered in evaluating cisplatin analogues, as with other prospective cancer drugs, is finding reproducible anti-tumour screens that are predictive of the behaviour of the drugs in the clinic. Progress is being made in the development of sensitive and resistant human tumour xenograft lines and this area should be monitored with interest, as it may provide a key to the development of a future platinum drug, hopefully with a wider range of activity than either cisplatin or carboplatin.

A prospective study of the relationship between serum vitamins A and E and risk of breast cancer

In an 8 year prospective study (1977-1985) on breast cancer, blood was taken from 5,086 women resident in Guernsey, and the serum stored at -20 degrees C. During this period 30 women developed the disease and their serum samples were analysed for vitamins A and E, and for retinol-binding protein (RBP). A further 288 age-matched control sera (up to 10 per pre-cancer case) were similarly analysed. No relationship was found between any of these substances and subsequent development of breast cancer. A significant correlation between increasing age and vitamin A (r = 0.46, P less than 0.001) and RBP (r = 0.36, P less than 0.001) concentrations was observed. There was also a trend for increased blood concentrations of vitamin E with age, but this was not significant. Serum RBP and vitamin A concentrations were highly correlated (r = 0.91, P less than 0.0001).

Thyroid function and the incidence of breast cancer in Hawaiian, British and Japanese women

Serum-free thyroxine (FT4) concentrations are lower in Hawaiian and Hawaiian Caucasian women than in Hawaiian Japanese, Hawaiian Filipino, Hawaiian Chinese, and English and Japanese mainland women. There is a high inverse correlation between FT4 and risk of breast cancer in these ethnic groups. Thyroid-stimulating hormone (TSH) concentrations, which are inversely correlated with FT4, generally show the same relationship.

Urinary androgen and 17-hydroxylated corticosteroid metabolites and their relation to recurrence rates in early breast cancer

The amounts of urinary androsterone and etiocholanolone are highly correlated with recurrence rates in patients with early breast cancer after treatment by mastectomy. A more efficient means of predicting the clinical course of the disease is obtained by using a ratio of these compounds to the amounts of individual 17-hydroxycorticosteroids in the urine. For instance, the ratio of androsterone to alpha-cortolone is particularly effective in identifying women with a high rate of recurrence, and this is largely independent of pathological stage and tumor grade.

Thyroid function in early breast cancer

Serum 'free thyroxine' was measured as a thyroid function index (TFI) in 238 women with early breast cancer and 107 normal controls. The mean TFI was significantly lower in the cases compared with controls. The TFI was not related to pathological stage but correlated with histological grade, with the highest values found in well-differentiated (grade I) and the lowest in anaplastic tumours (grade III). A similar result was obtained with the urinary and androsterone:aetiocholanolone (5 alpha:5 beta) ratio in that the ratio was significantly lower in patients with grade III than in those with grade I tumours. These results indicate that thyroid hormones may be involved in tumour cell differentiation. Patients with low 5 alpha/5 beta ratios had significantly faster recurrence rates than those with high ratios. A similar trend was found for the TFI. The TFI decreases after mastectomy and at 12 months after operation is still below the pre-operative basal level.

Knowledge of stimulus timing attenuates human evoked cortical potentials

To determine whether or not knowledge of stimulus timing influences the amplitude and latency of evoked cortical potentials, we have studied the evoked potentials of 24 adults under two contrasting conditions in which people knew or did not know the timing of tone stimuli by means of numerical perceptual cuing. Results demonstrated markedly smaller amplitude and significantly faster latency for the late components of vertex potentials evoked by stimuli whose timing subjects knew in advance. The cognitive act of knowing when auditory stimuli will occur attenuates the amplitude and facilitates the poststimulus timing of cortical evoked potentials.

Olfactory influences on the human menstrual cycle

Two groups of women were compared for the timing of the onset of their menstrual cycles. One group was rubbed on the upper lip (directly beneath the nose) with a mixture of alcohol and underarm perspiration collected from a single female donor. The other group was rubbed with plain alcohol. The group which received the perspiration showed a significant shift in the timing of their menstrual cycles which conformed closely with the donor's monthly cycle. This is a preliminary study which supports the hypothesis that the time of menstrual onset may be modified by olfactory cues.