The OMP-lacZ transgene mimics the unusual expression pattern of OR-Z6, a new odorant receptor gene on mouse chromosome 6: implication for locus-dependent gene expression

Reporter gene expression in the olfactory epithelium of H-lacZ6 transgenic mice mimics the cell-selective expression pattern known for some odorant receptor genes. The transgene construct in these mice consists of the lacZ coding region, driven by the proximal olfactory marker protein (OMP) gene promoter, and shows expression in a zonally confined subpopulation of olfactory neurons. To address mechanisms underlying the odorant receptor-like expression pattern of the lacZ construct, we analyzed the transgene-flanking region and identified OR-Z6, the first cloned odorant receptor gene that maps to mouse chromosome 6. OR-Z6 bears the highest sequence similarity (85%) to a human odorant receptor gene at the syntenic location on human chromosome 7. We analyzed the expression pattern of OR-Z6 in olfactory tissues of H-lacZ6 mice and show that it bears strong similarities to that mapped for beta-galactosidase. Expression of both genes in olfactory neurons is primarily restricted to the same medial subregion of the olfactory epithelium. Axons from both neuronal subpopulations project to the same ventromedial aspect of the anterior olfactory bulbs. Furthermore, colocalization analyses in H-lacZ6 mice demonstrate that OR-Z6-reactive glomeruli receive axonal input from lacZ-positive neurons as well. These results suggest that the expression of both genes is coordinated and that transgene expression in H-lacZ6 mice is regulated by locus-dependent mechanisms.

Does olfactory marker protein participate in olfactory neurogenesis?

Olfactory marker protein (OMP) is a phylogenetically conserved, 19-kDa, acidic, soluble protein found abundantly in mature olfactory sensory neurons. Its function has been enigmatic although recent evidence from studies on OMP null mice suggests that neurons lacking OMP exhibit altered physiological activity, including prolonged onset and recovery kinetics following stimulation. We have reported increased expression of OMP in individual surviving sensory neurons that have been deprived of their target, the olfactory bulb. Because olfactory epithelia deprived of their target also exhibit an increased rate of cell division we investigated the effect of recombinant OMP on cell division in organotypic cultures of fetal rat (embryonic day 19) epithelium grown for 3 days in vitro. After 3 days, cultures were given a 1-hr pulse of a mitotic marker, bromodeoxyuridine (BrdU), fixed and prepared for immunohistochemistry to determine the number of proliferating cells. We found a dose-dependent increase in the number of BrdU-positive cells/100-mm length of epithelium. The number of labeled cells increased incrementally, reached a plateau at 25 pM OMP/ml culture medium, 50% higher than in cultures with no OMP added, and remained at that level at 50 and 100 pM doses. Controls included trypsinized OMP and addition of equivalent volumes of TRIS buffer lacking OMP. These results, taken together with previous studies on several growth factors indicate that regulation of neurogenesis in olfactory tissue is a multifactorial process and that OMP may play a role.

Effects of mutation of the Olf-1 motif on transgene expression in olfactory receptor neurons

We have examined the effect of mutating the Olf-1 binding motif of the olfactory marker protein (OMP) promoter in determining olfactory neuron-specific gene expression in adult tissues and during embryonic development. The proximal Olf-1 motif located 170 nucleotides upstream of the transcription start site of the OMP gene was mutated to prevent its interaction with the Olf-1 factor in vitro. The wild-type and mutated fragments of the OMP gene extending from -239 to +55 nucleotides relative to the transcription start site were used to direct expression of a lacZ reporter gene in transgenic mice. The transgenic animals were analyzed for cell-specific and developmental expression of the reporter gene. We demonstrate that the mutation that prevents interaction of Olf-1 with its binding site does not alter the temporal and spatial patterns of gene expression in olfactory sensory neurons but does alter the specificity and level of expression in other neuronal populations. These observations are consistent with our demonstration that the mutated Olf-1 site interacts with nuclear proteins present in the central nervous system (CNS).

An enhanced olfactory marker protein immunoreactivity in individual olfactory receptor neurons following olfactory bulbectomy may be related to increased neurogenesis

Olfactory marker protein (OMP) is a 19-kD acidic protein found throughout the cytoplasm of mature olfactory receptor neurons (ORNs). Its function remains unknown. Following olfactory bulbectomy, the proportion of ORNs mature enough to express OMP declines greatly. However, in the few remaining mature ORNs, it has been observed that the intensity of OMP immunoreactivity (IR) appears to increase over that of ORNs on the unoperated side. We have now investigated this phenomenon quantitatively in rats subjected to unilateral olfactory bulbectomy. Results show that at all postbulbectomy survival periods examined quantitatively (3 days to 6 months), a significant decrease (19-37%) occurs in the transmission of incident light through OMP(+)-ORNs in bulbectomized versus unoperated olfactory epithelium (OE). Further, we also observed a consistent side-to-side difference in OMP IR in control unoperated animals. Possible explanations for these observations and their relation to the still unknown function of OMP are discussed. To test the possibility that OMP might serve a mitogenic role in the OE, recombinant OMP was added to organotypic explant cultures of fetal olfactory mucosa. Addition of OMP resulted in a dose-dependent increase in the density of bromodeoxyuridine-positive cells in the cultures, with a 50% increase occurring at the plateau OMP concentration of 25 pM.

Prenatal differentiation of mouse vomeronasal neurones

The vomeronasal organ (VNO) subserves basic chemosensory functions in rodents, mainly related to sexual behaviour. In order to understand early stages of the VNO structural maturation, we have undertaken an immunocytochemical analysis of the VNO of fetal mice. Our results demonstrate that Olfactory Marker Protein (OMP), a marker of differentiated chemosensory cells, is already expressed in vomeronasal neurones and their fibres projecting to the accessory olfactory bulb during the last week of gestation. However, in contrast to the adult, where its expression is restricted to the medial sensory neuronal component of the VNO, during fetal development OMP is also present in cells located in the lateral non-sensory epithelial component. Some other markers of nasal chemosensory neurones, such as GAP-43/B-50, Protein Gene Product 9.5 (PGP 9.5) and carnosine are also transiently expressed in this ectopic site. These results indicate that (i) significant morphological and biochemical maturation of the VNO is achieved before birth; (ii) transient cell populations, sharing the biochemical profile of the vomeronasal chemosensory receptors, occur in ectopic areas during fetal development.

LacZ and OMP are co-expressed during ontogeny and regeneration in olfactory receptor neurons of OMP promoter-lacZ transgenic mice

The ontogeny and cellular specificity of expression of beta-galactosidase activity and olfactory marker protein (OMP) are compared in olfactory tissue of the H-OMP-lacZ-3 line of transgenic mice. In this line the expression of lacZ is driven by a 0.3 kb fragment of the rat OMP promoter. During fetal development, lacZ expression is detectable in olfactory receptor neurons (ORNs) shortly after the initial appearance of endogenous OMP. The beta-galactosidase marker was observed only in mature olfactory receptor neurons where it co-localized with endogenous OMP. It was absent from immature neurons that express the growth associated phosphoprotein B50/GAP43. Lesion of the peripheral olfactory pathway by intranasal irrigation with Triton X-100 eliminated expression of both OMP and lacZ in the olfactory neuroepithelium. Subsequent regeneration of the full complement of olfactory receptor neurons was associated with co-expression of both OMP and beta-galactosidase activity. Neither OMP nor beta-galactosidase activity was induced in any other cell type of the regenerating olfactory mucosa. Thus, as little as 0.3 kb of the OMP promoter has the ability to target lacZ expression to olfactory receptor neurons in a temporally and spatially defined manner. We discuss the potential utility of this transgenic line for future studies of the olfactory system.

Olfactory glomeruli are innervated by more than one distinct subset of primary sensory olfactory neurons in mice

The rodent olfactory epithelium consists of a mosaic of primary sensory olfactory neurons (PONs) which express distinct putative olfactory receptor proteins. Recent evidence suggests that individual subsets of these sensory neurons project to separate glomeruli in the olfactory bulb (Vassar et al., [1994] Cell 79:981-991). In the present study we have identified two distinct subsets of primary sensory olfactory neurons (PONs) in the H-OMP-LacZ-6 transgenic mouse. In these transgenic mice, a LacZ reporter gene under the control of a 294 base pair element from the 5' promoter region of the olfactory marker protein (OMP) gene was expressed in a subset of PONs located in a discrete band of neuroepithelium in the nasal cavity. These LacZ positive neurons were not randomly located within this band but were more concentrated within a locus between endoturbinates IIb and III. The axons of these neurons densely innervated three adjacent and bilaterally symmetrical glomeruli present in the ventromedial olfactory bulb. Labeling of tissue sections with the plant lectin Dolichos biflorus (DBA) revealed an independent subset of PONs in the transgenic mice. These neurons were present in a wide region of the nasal cavity that included the neuroepithelial band containing the LacZ expressing neurons. The DBA labeled axons terminated in glomeruli in the rostromedial and dorsolateral olfactory bulb surfaces. Although the glomeruli innervated by the LacZ and DBA positive axons were predominantly non-overlapping there were glomeruli in the ventral olfactory bulb that were labeled by both DBA and LacZ markers. Eight different types of glomeruli were characterized. Most notably, glomeruli were identified which were innervated partially by both or by either subset alone. In these cases, axon subsets were observed to terminate within discrete subregions of a glomerulus. These results support the hypothesis that phenotypically distinct subsets of PONs converge on to the same glomeruli but also indicate that some glomeruli are innervated by more than one subset of sensory neuron. These findings have implications for understanding how the olfactory projection is formed and how olfactory information is processed.

Proximal regions of the olfactory marker protein gene promoter direct olfactory neuron-specific expression in transgenic mice

Olfactory marker protein (OMP) expression is highly restricted to mature olfactory neurons (ON). Less than 0.3 kb of upstream 5' flanking sequence of the OMP gene directs lacZ expression preferentially to ON in several independently derived lines of transgenic mice. A larger transgene with 0.8 kb of upstream flanking sequence also gave lacZ expression in ON and in a few ectopic sites in the central nervous system (CNS). In addition to the main olfactory epithelium, endogenous OMP is also expressed in chemosensory neurons of the vomeronasal and septal organs, and lacZ expression was detected in neurons of these sites as well. This confirmed the presence of regulatory sequences in the proximal portion of the OMP gene. Endogenous OMP expression in ON was normal in all transgenic lines. Strikingly, in several transgenic lines lacZ expression was restricted to subsets of ON. In one such line, ON axons were intensely stained for lacZ and projected to a subset of olfactory bulb glomeruli. Although identifiable subsets of ON and their termination fields have been described previously, this is the first demonstration of this phenomenon in transgenic mice. These lines of transgenic mice thus provide in vivo models for characterization of genetic elements regulating developmental and functional organization of the olfactory neuroepithelium.

Mechanism of neuroinvasion of Venezuelan equine encephalitis virus in the mouse

Venezuelan equine encephalitis virus (VEE) causes a biphasic disease in mice following subcutaneous inoculation in the footpad. In the initial phase, virus replicates primarily in the lymphoid tissues and induces a high titer viremia. Subsequently, the virus invades the central nervous system (CNS) from the circulation, and an encephalitis ensues. At the earliest times that VEE specific in situ hybridization signal was observed in the CNS, it was in areas of the brain involved in olfaction, leading to the hypothesis that virus may invade the brain from the circulation through the olfactory system. The results presented in this paper define the route of CNS invasion in experimental murine VEE disease initiated by subcutaneous inoculation. Virus circulating in the blood appears to seed specific areas of the peripheral nervous system during the viremic lymphoid phase of the illness. Virus replication within olfactory and dental tissues is followed by centripetal spread of virus along neural pathways. Virus enters the brain in a pattern reflecting the proximity of the peripheral invasion site to the CNS. Specifically, virus is first found in the brain within the structures of the olfactory system, followed by areas innervated by the trigeminal nerve. Virus later disseminates along fiber tracts and connected circuits within the brain, resulting in a disseminated meningoencephalitis. Surgical or chemical interruption of the olfactory system at the level of the olfactory neuroepithelium or the main olfactory bulb inhibited entry of VEE into the CNS through the olfactory nerve. However, the olfactory route is not absolutely required for CNS invasion, as virus invaded the CNS of olfactory ablated animals through the trigeminal nerve. These observations are consistent with a model of hematogenous seeding of the peripheral nervous system, followed by invasion of the CNS by direct neural spread.

Depression and parental bonding: cause, consequence, or genetic covariance?

It is shown how information on the direction of causation between variables may be obtained from a cross-sectional study of pairs of relatives. This method is applied to the study of the relationship between ratings of parents' rearing style and depression in their offspring. Adult female twins ascertained from a population-based registry in Viroffia completed the Center for Epidemiological Studies--Depression Scale (CESD) and a 7-item short form of the Parental Bonding Instrument (PBI) about each of their parents. Two dimensions of parental behavior, overprotectiveness and coldness, were analyzed jointly with depression data in both genetic factor and directional genetic models. Models that specify ratings of parents as a cause of depression in the offspring fit the data significantly better than models that specify depression as a cause of ratings of parents. A still better fit is obtained with models that specify common genetic variance to depression and ratings, though causal models with error variance perform almost as well. In general, ratings of fathers show more genetic and less shared environmental variance than ratings of mothers, which might arise from more consistent treatment of offspring by mothers than by fathers. No effect of children eliciting parental rearing style was detected with these data. The relative merits of instrumental variable, longitudinal, and family approaches to testing causal models are discussed.

Olfactory cytochrome P-450 immunoreactivity in mice is altered by dichlobenil but preserved by metyrapone

Antibodies to cytochromes P-450NMa and P-450NMb (CYP2A and CYP2G1, respectively) (P-450 nomenclature by Nebert et al., DNA Cell Biol. 10, 1- (1-14) 14, 1991) were used to assess the effects of the herbicide dichlobenil on the distribution of these olfactory-specific isozymes in the olfactory mucosa. Twenty-eight hours after a single dose (12 mg/kg) of dichlobenil, characteristic regions of the olfactory mucosa showed signs of necrosis in H&E stained sections. Accompanying this was a dramatic reduction in P-450 immunoreactivity in Bowman's glands of the olfactory mucosa, and an apparent redistribution of P-450 immunoreactivity within sustentacular cells. Treatment of mice with metyrapone, a P-450 inhibitor, at 10 min prior to and 2, 4, 6, and 8 h after a single dichlobenil injection, provided some protection against the damaging effects of dichlobenil. Both the gross and subcellular appearance of P-450 immunoreactivity in metyrapone/dichlobenil treated mice was similar to controls. Western blot analysis of P-450 expression following dichlobenil or metyrapone/dichlobenil treatment was generally consistent with immunohistochemical findings. These studies support previous reports that dichlobenil-induced olfactotoxicity is cytochrome P-450 mediated.

Receptor neuron losses result in decreased cytochrome P-450 immunoreactivity in associated non-neuronal cells of mouse olfactory mucosa

Immunohistochemical and immunoblot analyses were used to investigate nasal cytochrome P-450 distribution in mice with either unilateral naris closure for 3, 4, or 5 months, or olfactory bulbectomy. P-450 immunoreactivity was observed only in the supporting cells and Bowman's glands of the olfactory mucosa. Immunoreactivity was clearly reduced in rostral regions of the open-side olfactory mucosa where losses of receptor neurons resulted from 3 to 5 months of closure. Closed-side immunoreactivity was similar to controls. In 4 month closure animals that had regrown their receptor neurons, open-side immunoreactivity was comparable to controls. Olfactory bulbectomy also depressed P-450 immunoreactivity. These data suggest that presence or absence of receptor neurons markedly affects P-450 expression in nonneuronal cells of the olfactory mucosa.

A practicum in clinical nutrition as the internship component of an integrated masters/internship program

In September 1990, Chedoke McMaster Hospitals (CMH) admitted two students to the Practicum in Clinical Nutrition. This program was developed at CMH in affiliation with the graduate programs in nutrition offered at McMaster University and the University of Guelph. This is the first program in Canada to integrate a graduate nutrition degree at the Master's level with a clinical nutrition training program. The purpose of this paper is to describe the need, goals, educational philosophy, developmental process and anticipated benefits of this practicum.

Orbital dystopia: attempts to evaluate the results of surgery

This study has shown that surgery for hypertelorism or vertical orbital dystopia gives very satisfying results overall to the patients and their families and leads to a modest but highly significant objective improvement in appearance after surgery, as perceived by panels of laymen or hospital staff not known to the patients. The complexities of the methodology of panel assessments of appearance are discussed. The results of this study confirm the need to go beyond our traditional methods of assessing surgical outcome simply within our specialty.

Acute hamstring injuries in rugby players: The influence of positioning during ice therapy on muscle length

The effect on muscle length of positioning with ice application to acute hamstring injuries in rugby players was examined. Ice was applied with the hamstring muscle group in either the lengthened or the shortened position. Players with grade I or II hamstring injuries were randomly allocated (via the randomized block method) to the different treatment methods. The active hamstring length of the injured leg was measured by means of knee extension before and after treatment on days 1, 2 and 3 post-injury. The uninjured leg was measured on days 1 and 3.The discussion of results covered only the clinical observations since the experimental group was too small for statistical analysis.

Erythrocyte acid phosphatase phenotype and gestational length: no relationship in a sample of 3001 births

Erythrocyte acid phosphatase (ACP1) phenotype was examined in 3001 Caucasian infants born at the University of Michigan Women's Hospital. Contrary to reports from other studies, there was no relationship between the ACP1 phenotype and risk of preterm birth in either the total sample or when the sample was subdivided by sex of infant.

Binding studies of three water-soluble polycationic porphyrins with human serum albumin

The binding stoichiometry and equilibria of three polycationic water-soluble porphyrins with human serum albumin (HSA) have been determined by fluorescence quenching and filtration methods in 0.1M phosphate buffer, pH 7.2 at 25 degrees. For one porphyrin the binding equilibrium was also measured by measuring the lifetime of tryptophan and also by measuring the polarization of bound porphyrin. Energy transfer between the porphyrin and the tryptophan residue of HSA has been studied.

Test for the effects of 60-Hz magnetic fields on fecundity and development in Drosophila

Ramirez et al (1983) reported reduced egg laying by Drosophila melanogaster and reduced survival of those eggs to adulthood when adult flies were exposed to magnetic fields. In a similar study, no effects from exposures of Drosophila to 1-mT, 60-Hz magnetic fields were found.

Implantation, abortion, and birth after in vitro fertilization using the natural menstrual cycle or follicular stimulation with clomiphene citrate and human menopausal gonadotropin

The incidence of pregnancy and abortion was analyzed in 1679 patients having embryos replaced after oocyte recovery and in vitro fertilization in order to alleviate their infertility. In these patients, 364 pregnancies were achieved and 108 abortions occurred. Patients were treated either on their natural cycle, having a spontaneous luteinizing hormone (LH) surge to induce ovulation, or after ovarian stimulation using clomiphene citrate alone or in combination with human menopausal gonadotropin (hMG). The data were assessed in relation to the numbers of embryos replaced, the follicular stimulation and ovulation induction regime used, the dose of gonadotropins and the dose of antiestrogens, and the age of the patient. The most successful treatment for the number of live births per laparoscopy was the use of clomiphene citrate in combination with human menopausal gonadotropin followed by human chorionic gonadotropin (hCG) to induce follicular maturation and ovulation. This treatment produced a significantly higher (P less than 0.001) number of patients with multiple embryos (86.5%). There was no significant effect on pregnancy or abortion with a low (less than 400-mg) or high (greater than or equal to 400-mg) dose of clomiphene. The total dose of gonadotropins used did not influence the incidence of pregnancy or abortion. The use of hCG with hMG induced a significant (P less than 0.01) positive effect on the incidence of pregnancy. The incidence of pregnancy showed a progressive decline with increasing age but there was a highly significant (P less than 0.01) increase in the incidence of abortion with increasing age. With increasing numbers of embryos replaced, up to three, the incidence of deliveries increased.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of transient hyperprolactinemia on in vitro fertilization in humans

Hormonal stimulants of ovarian follicular maturation and anesthesia/surgery were examined for their effects on the concentration of plasma and follicular fluid PRL. Forty-seven patients undergoing in vitro fertilization for the treatment of infertility were selected at random for this prospective study. Patients given human menopausal gonadotropin and clomiphene citrate had significantly higher levels of plasma PRL compared to those given clomiphene only. Anesthesia/surgery elevated plasma PRL levels in all patients, by as much as 50-fold and to as high as 7878 mIU/liter. Follicular fluid PRL levels were correlated with preanesthetic plasma PRL concentrations, but the latter were not correlated with plasma 17 beta-estradiol. Elevated plasma or follicular fluid PRL concentrations had no effect on in vitro fertilization of oocytes or embryonic development. Although not significant, the incidence of pregnancy was highest in the group of patients with the lowest preanesthetic plasma PRL levels.

Responses of Lambs To Model Ewes

Abstract

Life sized models of sheep were used to determine the importance of sound and movement in eliciting orientation and approach of lambs. Dalesbred and Jacob lambs were tested at 3 weeks of age with two models, one of which appeared to be grazing while the other moved its head or bleated or both bleated and moved. Lambs were tested twice; their behaviour was recorded to note 1) time of orientation to models and approach; 2) positive or negative response; 3) approach within 2 m of the models. The Dalesbred lambs ran faster than the Jacobs towards the models, and more Dalesbreds responded positively on the second test. Both breeds responded more quickly to the vocal models than to the silent models; there was no difference in time of response to moving and non-moving models. 90% lambs approached and looked at the models on the first test, 51 % responded on the second test. All lambs that responded went up close to bleating models, but not to moving models. Movement did not increase attraction and seemed to deter close investigation, whereas vocalisation made the models most attractive to the lambs.

A fatal case of creosote poisoning

A case of fatal creosote poisoning is described. On presentation, extensive oropharyngeal ulceration was noted and gastric lavage withheld. Post-mortem examination showed an intact oesophagus and stomach.

Impaired granulocyte adherence in mildly diabetic patients: effects of tolazamide treatment

Granulocyte adherence in 10 of 15 untreated asymptomatic hyperglycemic diabetic outpatients (mean fasting glucose +/- SEM, 289 +/- 16 mg/100 ml) was 62 +/- 7% of control values. After treatment (2--4 wk) with tolazamide (500 mg daily), adherence to the nylon fiber columns employed in this study returned to control levels in the seven patients whose fasting glucose levels fell, (mean, 192 +/- 16 mg/100 ml) and deteriorated in the three in whom fasting hyperglycemia worsened. Results of this study indicate that, even in some mildly diabetic patients, a reduction in granulocyte adherence similar to that found in insulin-dependent diabetics may impair the inflammatory response.

Pharmacokinetics of cefamandole and ampicillin in experimental meningitis

The penetration of cefamandole and ampicillin into the cerebrospinal fluid of rabbits with and without pneumococcal meningitis was evaluated. In normal animals, a mean maximum concentration of 0.22 +/- 0.13 microgram of cefamandole per ml was measured in the spinal fluid after a dose of 150 mg/kg given intramuscularly; with 25 and 50 mg/kg doses, no antibiotic was detected in the cerebrospinal fluid. With ampicillin, in intramuscular doses of 200 and 300 mg/kg, the mean maximum concentrations encountered in the cerebrospinal fluid were 1.59 +/- 0.4 and 1.47 +/- 0.44 microgram/ml, respectively. Penetration of cefamandole, and to a lesser extent ampicillin, was increased after 24 h of experimental meningitis. With cefamandole, the concentration of drug in the cerebrospinal fluid exceeded the usual inhibitory concentration for Haemophilus influenzae only with the 150 mg/kg dose. After 48 h of meningitis, there was a trend toward higher levels of antibiotic in the cerebrospinal fluid, but the difference between animals infected 24 versus 48 h was not statistically significant. In animals with meningitis, serum concentrations after 150 mg of cefamandole per kg and both ampicillin doses studied were 32 to 38% lower than the serum levels achieved in normal rabbits after identical doses of antibiotic.

Impaired granulocyte adherence. A reversible defect in host defense in patients with poorly controlled diabetes

When the ability of granulocytes from 10 poorly controlled diabetic patients with fasting hyperglycemia and no evidence of ketoacidosis (mean fasting glucose 293 +/- 20 mg. per 100 ml.; mean +/- S.E.M.) to adhere to a nylon fiber column was assessed, the number of adherent granulocytes from whole blood was only 53 +/- 6 per cent of the values observed in controls. After antidiabetic treatment for one to two weeks and lowering of fasting glucose levels (mean 198 +/- 29 mg. per 100 ml.), adherence improved significantly (p less than 0.01) in the diabetics; however, their values were still subnormal (diabetic 74 per cent +/- 8 of control; p less than 0.02). Adherence values before and after treatment correlated with the fasting glucose level (r = 0.88, p less than 0.001). These findings suggest that, in addition to previously reported abnormalities in migration and the ingestion and killing of bacteria, granulocyte adherence may also be impaired in poorly controlled diabetic patients. This functional abnormality correlates directly with the fasting glucose and is reversed by insulin treatment. A defect of this type may compromise the normal inflammatory response in some diabetics and impair their capacity to resist infection.

The effect of anti-insulin serum and alloxan-diabetes on the distribution and multiple forms of hexokinase in lactating rat mammary gland

1. The distribution and multiple forms of hexokinase activity in lactating rat mammary gland were investigated in alloxan-diabetic rats and in rats treated with anti-insulin serum. It was found that 46% of the total hexokinase of mammary-gland tissue from control rats was in the particulate fraction, but this percentage was decreased in the alloxan-diabetic rats to 11% of the total hexokinase. The hexokinase activity of the soluble fraction was not significantly altered but there was a decrease in the type II/type I quotient. 2. The early changes that occurred on insulin deprivation were studied 1hr. after administration of anti-insulin serum to lactating rats, at which time the hexokinase bound to the particulate fraction had decreased to 11% of the control value and that in the soluble fraction had increased by approx. 50%. The hexokinase type II/type I quotient in the soluble fraction was significantly decreased. These results suggested that there was a release of particulate-bound hexokinase in rats treated with anti-insulin serum.

Effect of alloxan-diabetes and treatment with anti-insulin serum on pathways of glucose metabolism in lactating rat mammary gland

1. The overall metabolic changes in lactating mammary gland in alloxan-diabetic and anti-insulin-serum-treated rats were assessed by measurement of the incorporation of (14)C from specifically labelled glucose, pyruvate and acetate into carbon dioxide and lipid, together with measurements of enzymes concerned with the pentose phosphate pathway and with citrate metabolism. 2. Alloxan-diabetes depressed the rate of formation of (14)CO(2) from [1-(14)C]glucose and [2-(14)C]glucose to approx. 10% of the control rate; this was partially reversed by addition of insulin in vitro. The quotient Oxidation of [1-(14)C]glucose/Oxidation of [6-(14)C]glucose fell from a value of 17.6 in the control group to 3.9 in the diabetic group and was restored to 14.3 in the presence of insulin in vitro. In keeping with these results it was shown that glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were significantly decreased in alloxan-diabetic rats. 3. Alloxan-diabetes depressed the decarboxylation and the oxidation of labelled pyruvate, but not the oxidation of labelled acetate. 4. The synthesis of lipid from specifically labelled glucose was greatly decreased, that from [2-(14)C]pyruvate was almost unchanged and that from [1-(14)C]acetate alone was increased in alloxandiabetic rats. However, the stimulation of lipid synthesis from acetate by glucose was small in the alloxan-diabetic rats compared with the controls. Insulin in vitro partially reversed all these effects. Both citrate-cleavage enzyme and acetate thiokinase activities were decreased in alloxan-diabetic rats. 5. Treatment of rats with anti-insulin serum depressed the formation of (14)CO(2) from [1-(14)C]glucose and [2-(14)C]glucose, but increased that from [6-(14)C]glucose. This was completely restored by the presence of insulin in vitro. The quotient Oxidation of [1-(14)C]glucose/Oxidation of [6-(14)C]glucose fell from a value of 17.6 in the control group to 3.8 in the anti-insulin-serum-treated group. There were no changes in the activity of glucose 6-phosphate dehydrogenase or 6-phosphogluconate dehydrogenase, but the hexokinase distribution changed and the content of the soluble fraction increased significantly. 6. The synthesis of lipid from specifically labelled glucose was depressed in anti-insulin-serum-treated rats; this effect was completely reversed by addition of insulin in vitro to the tissue slices.

Effect of thyroidectomy on pathways of glucose metabolism in lactating rat mammary gland

1. Assessment of the overall metabolic changes in lactating mammary gland after thyroidectomy has been made by measurement of the incorporation of (14)C from specifically labelled glucose, pyruvate and acetate into (14)CO(2) and (14)C-labelled lipid in the experimental rats and in sham-operated control animals. 2. Thyroidectomy depressed the oxidation of (14)C-labelled substrates, an effect still apparent when the control rats were pair-fed with thyroidectomized rats; however, the ratio of oxidation of [1-(14)C]glucose/oxidation of [6-(14)C]glucose was unaltered. In parallel with these studies it was revealed that the activities of hexokinase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP-linked isocitrate dehydrogenase were all lower in the thyroidectomized group than in the pair-fed control group. 3. Thyroidectomy also lowered the incorporation of (14)C-labelled substrates into (14)C-labelled lipid, an effect further studied by measurement of the activities of citrate-cleavage enzyme and acetate thiokinase. Restricting the food intake of the control rats to that of the thyroidectomized group lowered the activity of citrate-cleavage enzyme, but no further depression was observed on thyroidectomy. The oxidized and reduced nicotinamide nucleotide content of mammary tissue was shown to be decreased in the thyroidectomized rats compared with the control rats.

Multiple forms of glucose-adenosine triphosphate phosphotransferase in rat mammary gland

Measurements have been made of the total hexokinase activity and of the relative amounts of types I and II hexokinase in rat mammary gland and at different stages of the lactation cycle. The total hexokinase activity increased during lactation, that of type II increasing to a greater extent than that of type I; the type II/type I activity ratio rose from a pregnancy value of about 1 to a mid-lactation value of 3, returning to 1 on involution. The changes in type II hexokinase activity during the lactation cycle parallel the changes in the insulin sensitivity of mammary-gland tissue. A study of the effect of alloxan-diabetes on mammary-gland hexokinase during the mid-lactation period revealed that, although the total glucose-phosphorylating capacity of the mammary gland was almost unchanged, the relative contributions of type I and type II hexokinases altered, decreasing the type II/type I activity ratio to about 1.

The effect of thyroidectomy on the pattern of fatty acids synthesized by mammary gland from lactating rats

Thyroidectomy decreased the content of short-chain fatty acids and increased the content of long-chain fatty acids in the mammary glands of lactating rats. This effect was replicated in the glands of untreated rats limited to the same food intake as the thyroidectomized animals. Thyroidectomy decreased the incorporation of [6-(14)C]glucose into short-chain fatty acids and increased the incorporation into longer-chain acids. Restriction of the food intake of untreated animals did not cause a similar shift of the incorporation pattern. The possibility that the thyroxine effect on lipogenesis is secondary to its effect on carbohydrate metabolism is discussed.