Developmental defects associated with glucosamine auxotrophy in Saccharomyces cerevisiae

Saccharomyces cerevisiae mutants, unable to make D-glucosamine owing to a defect in the enzyme 2-amino-2-deoxy-D-glucose-6-phosphate ketol-isomerase (amino-transferring) (EC 5.3.1.19), show aberrations both in sporulation and in vegetative growth. They grow normally on a medium of yeast extract, peptone, and dextrose (YEPD) containing D-glucosamine (1 mg/ml), and such cells accumulate 4 to 5 times the amount of D-glucosamine present in wild-type cells cultured on YEPD alone. When such mutant cells are shifted to YEPD alone, they continue to increase in cell mass for about 10 hr (three to four cell cycles) and produce strings of beads in which the cells fail to separate. Although each of the "cells" contains a nucleus, electron micrographs of thin sections reveal that septation is defective apparently owing to the inability to synthesize chitin, which forms the primary septum in S. cerevisiae. The viability of such cultures drops rapidly after 3-5 hr, a fact attributable to lysis of the cells through wall defects in the septum region where gross disorganization is apparent. When the mutant cells grown on YEPD plus D-glucosamine are transferred to sporulation medium (1% potassium acetate), they proceed through meiosis to produce viable spores that appear to be altered only in the nature of the spore wall. The spores lack a dark-staining surface layer that is visible in thin sections prepared from wild-type cells, they are notably less hydrophobic than wild-type spores, and they are digested and lysed by glucanases that do not affect normal spores. All of these properties suggest that D-glucosamine is required for spore maturation and is used to synthesize a glucanase-resistant hydrophobic surface layer on the primary glucan spore wall. In agreement with this postulate, D-glucosamine synthesis and the activity of the isomerase do not appear until late in meiosis when tetranucleate cells are abundantly present in the sporulation culture.

Determination of lipid A and endotoxin in serum by mass spectroscopy

A quantitative technique for determining lipid A content of endotoxin added to serum by combined gas chromatography-mass spectrometry is described. This technique uses detection of the beta-hydroxymyristic acid content of Salmonella minnesota R595 lipopolysaccharide by selected ion monitoring at atomic mass unit of 315.4 The fatty acids produced on hydrolysis of serum containing lipopolysaccharide were extracted and the methyl esters were made. Silica gel chromatography was used to separate methyl esters of hydroxy fatty acids from other fatty acid methyl esters. Trimethylsilyl ether derivatives of the hydroxy fatty acid methyl ester fraction were quantitated by this technique. As little as 200 fmol of beta-hydroxymyristic acid could be detected.

The obesity syndrome and acanthosis nigricans. Acanthosis nigricans is a common cosmetic problem providing epidemiological clues to the obesity syndrome, the insulin-resistance syndrome, the thrifty metabolism, dyslipidaemia, hypertension and diabetes mellitus type II

Obesity and its consequences are arguably the chief public health problems facing the developed world. Obesity causes many fatal diseases, in particular cerebrovascular and cardiovascular disease. Acanthosis nigricans (AN) is a common cosmetic disability in pigmented ethnic groups. It may present with periorbital darkening or darkening of the neck or knuckles as well as acrochordons (skin tags) around eyelids, neck or axillae. The more classical AN of axillae and groins is less often a cosmetic disability, although it is an important physical sign. AN is very common in pigmented populations throughout the world, irrespective of domicile. It is rare in whites. AN is closely associated with all the features of the insulin-resistance syndrome (IRS), especially obesity. AN and IRS share a similar prevalence and epidemiology. IRS (also known as syndrome X or the deadly quartet) is characterized by insulin resistance (IR) and its associated conditions, including obesity, dyslipidaemia, hypertension and diabetes mellitus (DM) type II. The sequelae of IRS are cardiovascular and cerebrovascular disease. The origins of insulin resistance and its sequel, IRS, are debated. Insulin resistance can result from obesity. Also obesity usually presents before AN, hypertension or DM II. For these reasons it may be more helpful to recognize instead an obesity syndrome. The obesity syndrome is characterized by a genetically determined thrifty metabolism that protects subjects in famine conditions but which, in conditions of plenty, leads to weight gain with all its consequences, including hyperlipidaemia, hypertension, IR with DM II, and, in due course, cerebrovascular and cardiovascular disease. In pigmented races, AN is an important early manifestation of the obesity syndrome. AN helps identify persons at particular risk of developing the obesity syndrome, dyslipidaemia, hypertension and IR with DM II. Recognition of AN, therefore, offers important opportunities for health screening and preventative medicine.

Second primary cancers in patients with squamous cell carcinoma of the skin

The occurrence of second primary cancers was explored in patients with squamous cell cancer of the skin (SCC). The excess incidence subsequent to SCC was mainly in cancers related to sunlight and smoking, and in lymphoproliferative malignancies, it was largest (10-fold) in salivary gland cancer.

Characterization of a mannan-like oligosaccharide from Mycobacterium smegmatis

A nitrogen-free neutral mannooligosaccharide, similar in structure to the polysaccharide component of yeast mannoproteins, has been isolated from Mycobacterium smegmatis ATCC-356. It has a molecular weight of 3200 and is terminated at the reducing end by mannose. nuclear magentic resonance spectroscopy, methylation analysis, selective enzymic degradation and acetolysis indicates that the molecule consists of an alpha1 --> 6-linked backbone to which single mannose units are attached in alpha1 --> 2 linkage as sidechains.

The morpho-anatomy and histology of the pineal complex in a major Indian carp, Catla catla: identification of the pineal photoreceptor cells and their responsiveness to constant light and constant darkness during different phases of the annual reproductive cycle

In contrast to mammals in which the pineal gland is a discrete structure situated dorsally in the brain, the "pineal gland" in teleost fishes is composed of a number of separate but connected constituent parts, collectively described as the "pineal complex." In this paper, we have described the pineal complex in a common Indian carp, Catla catla, which exhibits an annual reproductive cycle. Attempts have been made to (a) provide an in-depth description of the structure of the pineal complex; and (b) identify the photoreceptor cells of the pineal, by exposing the animals to constant light (LL) and constant darkness (DD). Furthermore, we examined any possible influence of the reproductive status of the fish on the responsiveness of the pineal photoreceptor cells in C. catla following exposure to LL and DD. To this end, a total of four experiments were carried out during the four different phases of the annual reproductive cycle that is characteristic of this species. Each of these four experiments was carried out for a period of 30 days after which the fishes were sacrificed, different parts of the pineal complex were dissected out, and processed for histological and karyometric studies. Our results showed that the pineal complex in this species is composed of three separate but connected parts, (a) an end vesicle (EV); (b) a dorsal sac (DS); and (c) a long and thin pineal stalk (PS) that attaches the EV to the DS. Detailed karyometric and histo-morphologic studies following exposure of the animals to DD and LL showed that constant darkness led to a stimulatory effect on the pineal photoreceptor cells of the EV as evident from a significant increase in the nuclear diameter. In contrast, the nuclear diameter of the photoreceptor cells in animals subjected to constant light showed a significant reduction. Furthermore, the observed cellular changes in the EV of fish exposed either to LL or DD were independent of the stage of the gonadal cycle. The apparent lack of any cellular responses either in the PS, or in the DS, following exposure to LL and DD, suggests that in C. catla the photoreceptor cells are located only within the epithelial lining of the EV and that these cells respond in a manner similar to mammalian pinealocytes when subjected to comparable photoperiod-induced experimental conditions.

The structure of the pineal complex in a common Indian teleost, Catla catla: evidence for pineal-induced inhibition of testicular function within an annual reproductive cycle

The structure of the pineal complex and the annual reproductive cycle in a major Indian carp, Catla catla, were investigated in the present study. Additionally, given the well-known inhibitory effects of the pineal on reproductive function in mammals, attempts were made to investigate whether or not the pineal exerts an inhibitory influence on reproductive function in this piscine species as well. Sexually adult animals were utilized in all experiments. The cytomorphology of the pineal complex and a number of parameters for testicular function--such as testicular cytology, serum testosterone levels, and testicular activities of two steroidogenic enzymes, 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and delta5-3beta-hydroxysteroid dehydrogenase (delta5-3beta-HSD) were examined over a period of two years. Our studies showed that the pineal complex in this species consists of three separate but distinctly connected components: (a) an end vesicle (EV); (b) a long pineal stalk (PS); and (c) a dorsal sac (DS). Of these, the epithelial lining of the EV consists of cells that have rounded vesicular nuclei and long apical cytoplasmic processes that reach the lumen, features suggestive of photoreceptor cells. The cells of the PS have some similarity with those of the EV, while DS cells appear columnar and ciliated. With regard to gonadal activity, germ cell profiles revealed that this species has four distinct phases during the annual reproductive cycle: (a) preparatory (January-April); (b) pre-spawning (May-June); (c) spawning (July); and (d) post-spawning (August-December). During the spawning phase (July), seminiferous tubular diameter, percentage of late spermatids within seminiferous tubules, and serum testosterone levels showed the highest values compared to those obtained in most of the other phases of the reproductive cycle. Also in July, along with peak serum testosterone levels, the activities of 17beta-HSD and delta5-3beta-HSD were at their highest levels. In a correlation between the pineal cytology and testicular functional status, it was noted that both the nuclear diameter and the apical cytoplasmic projections of the EV photoreceptor cells showed a significant reduction, thus suggesting a reduced synthetic activity, during the month of July, the spawning phase of the reproductive cycle. In contrast, the same features of the EV cells during the other phases of the reproductive cycle showed an increased cellular and metabolic activity--a time when the gonads were less active and in a quiescent stage. These data suggest an inhibitory role of the pineal on gonadal function and thus provide additional credence to the concept that, as in higher mammals, there exists an inverse relationship between the pineal activity and gonadal function in teleost fishes as well.

Gametogenic responses of the testis in spotted munia (Lonchura punctulata; Aves) to oral administration of lithium chloride

In the present study, the effects of orally-administered lithium on testicular morphology were examined in the spotted munia (Lonchura punctulata), a seasonally breeding sub-tropical finch. Adult males were procured from natural populations during the month of August, a time when these birds begin to show seasonal reproductive maturity in an annual cycle. Both during the period of acclimation, and throughout the subsequent experimental period, the birds were maintained in an open aviary simulating natural environmental conditions. Lithium was dissolved in distilled water and was administered via the oral route by means of a commercially available stomach-tube. A total of five experimental groups were utilized. The first group (Group A) served as control and received lithium-free distilled water in a similar manner. In the remaining four groups, lithium was administered daily as follows: Group B (2.5 mEq/Kg body weight for 5 days); Group C (2.5 mEq/Kg for 10 days); Group D (5.0 mEq/Kg for 5 days) and Group E (5.0 mEq/Kg for 10 days). All lithium administrations were carried out between 14:00 and 15:00h. Twenty-four hours after the last oral lithium, final body weights were recorded, blood samples were obtained (by brachial vein puncture for the measurement of serum lithium) and the animals were sacrificed, and testes were collected for histological studies. Our results indicated that lithium treatment led to a significant reduction in testicular weight and seminiferous tubular diameter, and a marked degenerative changes in germ cells in that most of the spermatids and mature spermatozoa showed necrotic changes and were sloughed off from the seminiferous tubular epithelium. Complete desquamation and loss of germ cells, and their clump formation were also noted within many seminiferous tubular lumen. Notably these adverse effects were observed when serum lithium levels were within the therapeutic range for human. These results confirm our earlier report on lithium's adverse effects on testicular function, and extend further to show that lithium indeed has a significant adverse effect on the histomorphology, and, thus, the function of the testis in birds.

Influences of graded dose of melatonin on the levels of blood glucose and adrenal catecholamines in male roseringed parakeets (Psittacula krameri ) under different photoperiods

Effects of daily evening (just before the onset of darkness in a 24 h light dark cycle) administration of graded doses (25, 50, or 100 microg/100 g body wt./day for 30 days) of melatonin on the concentrations of blood glucose and adrenal catecholamines were studied in sexually active male roseringed parakeets under natural (NP; approximately 12L: 12D) and artificial long (LP; 16L: 8D) and short (SP; 8L: 16D) photoperiods. Blood samples and adrenal glands were collected from each bird during the mid-day on the following day of the last treatment. The concentrations of glucose in blood and epinephrine (E) and norepinephrine (NE) in the adrenals were measured. The results of the study indicated that exogenous melatonin induces hypo- or hyperglycemia depending on the dose of hormone administered as well as to the length of photoperiod to which birds were exposed. The levels of E and NE in the adrenals were shown also to vary in relation to photoperiod and the dose of melatonin administered. But the nature of the influence of melatonin becomes different under altered photoperiodic conditions. It appears that short photoperiods are more effective than long photoperiods as a modulator of glycemic and adrenal catecholaminergic responses to exogenous melatonin. A statistically significant correlation between the levels of blood glucose and that of E and NE in the adrenals was found in the control birds, but not in the melatonin treated birds. The results suggested that the responses of blood glucose and adrenal catecholamines to the treatment with melatonin in the roseringed parakeets may not be dependent on each other.

Influence of photoperiods on glycemic and adrenal catecholaminergic responses to melatonin administrations in adult male roseringed parakeets, Psittacula krameri Neumann

Effects of daily (one hour prior to onset of darkness) injection of melatonin (25 micrograms/100 g body wt. for 30 days) on concentrations of blood glucose and adrenal catecholamines were studied in adult male roseringed parakeets, P. krameri under both natural (NP; about 12L:12D) and artificial long (LP; 16L:8D; lights were available in between 0600 and 2200 hrs) or short (SP; 8L:16D; lights were available between 0600 and 1400 hrs) photoperiodic conditions. The results indicate that neither LP, nor SP as such exerts any significant effect on blood glucose titre of control (vehicle of hormone administered) birds. Treatment with melatonin, however, induced hyperglycemia in both NP and LP bird groups, but hypoglycemia in SP birds. Unlike glycemic levels, amount of epinephrine (E) and norepinephrine (NE) in adrenals of control birds exhibited significant changes under altered photoperiods. A decrease in E and an increase in NE were noted in adrenals of both LP and SP birds. Exogenous melatonin in NP birds also caused a decrease in E and concomittant rise in NE levels. On the other hand, treatment of melatonin in both LP and SP bird groups resulted in an increase in the quantity of both E and NE compared to respective values in adrenals of melatonin injected NP birds. However, relative to the amount of E and NE in adrenals of placebo treated LP and SP birds, significant effect of melatonin treatment was observed only in SP birds. The results suggest that influences of exogenous melatonin on the levels of both blood glucose and adrenal catecholamines are largely modulated by short rather than long photoperiods.

Role of light in the mediation of acute effects of a single afternoon melatonin injection on steroidogenic activity of testis in the rat

Young adult male rats, maintained either in an LD 12 : 12 or in continuous illumination (LL) for one week, were given a single injection of 25 microg melatonin/100 g body wt or ethanolic-saline (control) at 17.00 h. Animals from each group were sacrificed at 11.00 h on the following day. The activity of two important steroidogenic enzymes, 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) and delta(5)-3 beta-hydroxysteroid dehydrogenase (delta(5)-3 beta-HSD), and serum concentrations of testosterone, were measured following highly specific and sensitive spectrophotometric techniques and RIA, respectively. A significant decrease in the activity of both the steroidogenic enzymes was noted in the testes of melatonin-treated rats maintained under normal light-dark schedules, but this response was found to be lacking in the LL rats. However, no significant changes in the level of serum testosterone were noted in either group of melatonin-treated rats from the values in respective groups of ethanolic saline-administered LD and LL rats. Exposure of ethanolic saline-injected rats to continuous light also did not cause any change in the steroidogenic activity of the testis from those in LD rats. The study indicates that continuous light as such does not affect the endocrine function of testis but abolishes suppressive effects of melatonin on the steroidogenic activity of the testis in rat.

Lithium-induced alterations in the testis of the male roseringed parakeet (Psittacula krameri) : evidence for significant structural changes and disruption in the spermatogenetic activity

In this report, we have examined the effects of lithium on testicular morphology in a male subtropical wild avian species, the roseringed parakeet (Psittacula krameri). Adult male birds were collected during the months of February-March, a time when the testicular gametogenic activity in these seasonally breeding birds is at its peak. They were injected, intramuscularly, twice daily (07:00 and 19:00 h) with lithium chloride (Sigma Chemical Company) at a dosage of 0.5 mEq/Kg body weight either for 5 or 10 days. A significant decrease in both the absolute and relative testicular weights was evident in the lithium-treated birds as compared to those of the saline-injected control animals. Light microscopic studies of the testis in the lithium-treated animals showed a wide range of degenerative changes. These included a) a significant reduction in the diameter of seminiferous tubules; b) necrosis and exfoliation of most of the germ cells in the seminiferous tubular lumen with the exception of the spermatogonia; and c) a significant reduction in the number of mature spermatozoa in the tubular lumen. These degenerative changes were dependent on the duration of lithium treatment and were evident when the plasma lithium concentrations were well below the human therapeutic range. Leydig cell morphology was not affected by lithium however. Our results provide the first experimental evidence of lithium's adverse reproductive function in an avian species. These data provide further support to the view that lithium adversely affects the male reproductive system and that these effects extend beyond mammalian species.

Influence of methyl parathion on gametogenic and acetylcholinesterase activity in the testis of whitethroated munia (Lonchura malabarica)

Adult male whitethroated munias, Lonchura malabarica (Aves; Passeriformes), were orally administered with methyl parathion (O, O-dimethyl O-(4-nitrophenyl) phosphorothioate), an extensively used organophosphate pesticide, in graded sublethal dose (5 micro g-, or 10 micro g-, or 20 micro g/100 g body wt/day) for variable durations (1-, 5-, or 10 day/s) during their peak reproductive activities in an annual gonadal cycle. No subtle changes in the feeding behavior, mobility, and body weight were noted between the control and different groups of pesticide-fed birds. As a result of the treatment, the paired testicular weight became reduced significantly only after 10 days at 10 micro g and 20 micro g dose levels, but significant decrease in the number of tubules containing healthy germ cells occurred even after single administration of methyl parathion (MP) at the lowest dose (5 micro g/100 g). With the increase in dose and progress of treatment, the number of tubules with healthy germ cells became gradually decreased. The activity of acetylcholinesterase (AChE) in both the brain and testes of MP-treated birds was inhibited in a dose and duration dependent manner. A significant negative correlation was observed between the number of tubules containing degenerated germ cells in the testis and the AChE activity in both the brain and testes of MP-administered birds. However, no remarkable changes in the cytomorphological features, including the nuclear diameter of Leydig cells, were noted in any testis of the pesticide-treated munias. The results of the present investigation suggest that methyl parathion ingestion is harmful to male gametogenic functions in the studied passeriform bird, and the given pesticide may exert its antigonadal effect by impairing cholinergic functions of the brain and/or testes.

Diurnal sensitivity of the testes to exogenous testosterone propionate in sexually regressed whitethroated munia Lonchura malabarica

The testes in different groups of whitethroated munia (Lonchura malabarica) were studied following exogenous treatment of testosterone propionate (1 mg/100 g body wt./day) at 06.00 h or 14.00 h or 22.00 h for 15 consecutive days during the quiescent phase of the annual testicular cycle. The testicular conditions in each group of testosterone treated and appropriate control (administered only with the vehicle of hormone at corresponding time-points) group of birds were analyzed by the studies of paired testicular weight, seminiferous tubular diameter, spermatogenetic index, and cytology of the testicular germ cells. The results of the study revealed that exogenous testosterone was stimulatory to the testicular functions irrespective of the time of treatment. The gametokinetic response of the testes to exogenous testosterone also did not show any statistical difference among the birds treated at different hours of the day. The present study demonstrates for the first time that the responses of the testes to exogenous testosterone during the post-breeding phase in an annual testicular cycle of a wild bird does not vary with the time of administration.

Castration and testosterone induced changes in the pinealocytes of roseringed parakeet, Psittacula krameri, during different phases of the annual testicular cycle

The pinealocytes in male roseringed parakeets (Psittacula krameri) were studied following bilateral castration and/or therapeutic administration of testosterone during the preparatory (June-July), progressive (Nov.-Dec.), pre-breeding (Jan.-Feb.) and breeding (March-April) phases of the annual testicular cycle. The responses of the pineal to either treatment were found to be almost identical throughout the investigation. In each reproductive phase, the pineal appeared to be hypertrophied following castration and the effect was reversed by therapeutic administration of testosterone, while hormonal treatment to the intact parakeets induced regressive changes in the pinealocytes. Collectively, the results of the current study support the hypothesis that the testis through its hormone testosterone exerts inhibitory influences on the activity of pineal, and may thus be considered as being involved in the determination of an inverse relationship between the pineal and the testis during the annual cycle of free-living parakeets.

Changes in brain neurotransmitters in rodent malaria

Changes in brain neurotransmitters [5-hydroxytryptamine (5-HT), norepinephrine, histamine and dopamine] were studied in Plasmodium berghei-infected mice and rats. 5-HT and norepinephrine contents of brain decreased significantly in Plasmodium berghei-infected mice and rats, but histamine and dopamine contents remained unaltered. Decreased 5-HT and norepinephrine contents of brain may play a role in cerebral vasodilatation in malaria.

Effects of progesterone on some brain neurotransmitters in intact rats

Effects of progesterone on four neurotransmitters (viz, noradrenaline, 5-HT, dopamine and histamine) of brain were seen in rats with intact ovaries. It was found that progesterone lowers the noradrenaline concentration in medulla, pons, midbrain, hypothalamus, thalami and pituitary, uniformly, when the rats were killed within 4 hours of progesterone injection. At longer intervals (48 hrs) effects of progesterone were seen when progesterone in heavy dose was administered to rats pretreated with estrogen. It is likely that one of the modes of action of the oral contraceptives may be the reduction of noradrenaline content in selected areas of brain, by progesterone. It is also suggested, therapeutic usage of progesterone carries the risk of development of depression in the user.

Importance of photoperiods in determining temporal pattern of annual testicular events in rose-ringed parakeet (Psittacula krameri)

Male rose-ringed parakeets (Psittacula krameri) were transferred to a long photoperiod (LP; LD 16:8) or a short photoperiod (SP; LD 8:16) for 45 or 90 days on four dates corresponding to the beginnings of different reproductive phases in an annual testicular cycle, and testicular responsiveness was evaluated by comparison with the testicular volume, weight, seminiferous tubular diameter, and germ cell profiles of birds in a natural photoperiod (NP). Exposure of birds to LP during the progressive phase (November) led to precocious maturation of testes after 45 days, but induced regression at 90 days. After showing retarded gametogenic functions at 45 days, parallel (November) SP birds exhibited an accelerated rate of germ cell formation at day 90. During the prebreeding phase (January), there were no remarkable differences in any features of testes among NP. LP, and SP birds at 45 days, but gonadal involution in LP parakeets and active spermatogenesis in SP birds occurred after 90 days. The testes did not show any response to LP or SP for 45 and 90 days when the birds were transferred to altered photoperiods during the breeding (March) and preparatory (June) phases, indicating that the parakeets were photorefractory for at least 6 months (March through September). The results also suggest that initiation and termination of seasonal gametogenic activity in parakeets are possibly functions of endogenous rhythmicity or extraphotoperiodic environmental factors. Duration of light may have certain influences on the attainment of annual peak in spermatogenesis, but in all probability the species has a low photoperiod threshold for induction of testicular growth.

Involvement of cyclic guanosine monophosphosphate (cGMP) and cytosolic guanylate cyclase in the regulation of synaptic ribbon numbers in rat pineal gland

In the rat pineal gland N-acetyltransferase (NAT) activity and synaptic ribbon (SR) numbers display a circadian rhythm. It is well-known that NAT activity is regulated by adrenergic mechanisms involving cyclic adenosine monophosphate (cAMP) as a second messenger. However, the mechanism involved in the regulation of SR numbers has not been established so far. In the present in vitro study, we have investigated the effects of 8-bromo-cyclic guanosine monophosphate (8-bromo-cGMP), a cyclic guanosine monophosphate (cGMP) analog, and stimulation of guanylate cyclase on SR numbers. Incubation with 8-bromo-cGMP increased SR numbers in a dose- and time-dependent manner. Further, stimulation of the cytosolic guanylate cyclase also resulted in increased SR numbers. Adrenergic agonists stimulated cGMP but did not alter SR numbers. These findings suggest that cGMP is involved as a second messenger in the regulation of SR numbers. Since the adrenergically stimulated increase in cGMP did not influence SR numbers, a non-adrenergic cGMP metabolic pathway seems to be involved in the regulation of SR numbers in the rat pineal gland.

Development of day-night rhythmicity in "synaptic" ribbon numbers in the pinealocytes of posthatch chicks kept under either natural photoperiodic conditions or continuous illumination

Pineal synaptic ribbons (SR) undergo characteristic changes over a period of 24 hr under natural photoperiodic conditions in various vertebrates, being low in number during daytime and elevated at night. During posthatch development of chicks, the rhythmicity of SR numbers is reported to appear at the age of about 2 weeks. Because the influence of external light during the growth phase of chicks on the development of day-night rhythmicity in SR numbers is unknown, we studied day-night differences in SR numbers in the pinealocytes of chicks at the posthatch ages of 15, 17, and 19 days; chicks had previously been kept under natural photoperiodic conditions or continuous illumination. Under natural photoperiodic conditions a statistically significant nocturnal (midnight) rise in SR numbers over the value of midday was seen in the pineal of 17- and 19-day-old chicks, but not in 15-day-old chicks. SR numbers in the pinealocytes of continuously illuminated chicks did not show any day-night rhythmicity on days either 15 or 17, but exhibited significant day-night differences on day 19 posthatch. These findings suggest that continuous illumination, which is known to dampen circadian rhythmicity of melatonin secretion in the chick pineal, causes a delay, but not a total suppression of the mechanism involved in the ontogenic development of diurnal rhythmicity in SR numbers in the pinealocytes of chicks.

The effects of short pulses of light at night on numbers of pineal "synaptic" ribbons and serotonin N-acetyltransferase activity in male Sprague-Dawley rats

To characterize further the functionally enigmatic "synaptic" ribbons (SR) of the mammalian pineal gland and to study possible relationships to melatonin synthesis, in the present investigation rats were exposed to short pulses of light at night when both SR numbers and serotonin N-acetyltransferase (NAT) activity are high in comparison to day-time values. Male Sprague-Dawley rats were killed at 13:00 and 01:00 h, respectively, and at 01:10 and 02:00 h after exposure to light for 10 and 60 min, respectively. The pineals were rapidly taken out and cut sagittally in half. One half was processed for electron-microscopic quantitation of SR numbers and the other half for NAT determinations. It was found that both SR numbers and NAT activity decreased significantly when the animals were exposed to light at night. Although both parameters showed corresponding changes, there was no clear-cut correlation between SR numbers and NAT activity in individual animals within a group, except after exposure to light for 60 min when a positive correlation (R = 0.939; p less than 0.05) existed. After exposure to light the electron-lucent vesicles of the SR decreased in number, but the length of the SR was unchanged. These results show that numbers of pineal SR can be easily and quickly manipulated and that the presently used model may be ideal in studying the poorly understood mode in which degradation of SR occurs.

Establishment of beta-hydroxy fatty acids as chemical marker molecules for bacterial endotoxin by gas chromatography-mass spectrometry

Selected ion-monitoring gas chromatography-mass spectrometry was used for detection of beta-hydroxy fatty acids as an independent assay for the presence or absence of endotoxin in materials claimed to induce nonspecific activation of Limulus amoebocyte lysate. To this end, suspensions of gram-negative and -positive bacteria, one fungal species, cerebrospinal fluid, and hollow-fiber hemodialyzer rinses were assayed for endotoxin by gas chromatography-mass spectrometry and the Limulus amoebocyte lysate assay. Good qualitative agreement was shown for both methods when suspensions of test organisms were assayed. Two false-negative results were obtained by gas chromatography-mass spectrometry assays of cerebrospinal fluid and were shown to be a result of insufficient endotoxin in the cerebrospinal fluid specimens for detection by gas chromatography-mass spectrometry. Hemodialyzer rinses were Limulus assay positive; however, no beta-hydroxy fatty acids were detected by gas chromatography-mass spectrometry. These data were compared with data obtained from USP rabbit pyrogen tests of the rinse materials (nonpyrogenic) and chemical characterization of the Limulus assay-reactive rinses, which showed the rinses to be cellulosic in nature. It is suggested that beta-hydroxy fatty acids, as assayed by selected ion-monitoring gas chromatography-mass spectrometry, be used as chemical marker molecules for the presence or absence of endotoxin in materials reported to cause nonspecific activation of Limulus amoebocyte lysate.

Properties of binding of Escherichia coli endotoxin to various matrices

Binding of Escherichia coli O127:B8 endotoxin to a variety of resins and column materials was investigated by measuring the beta-hydroxy myristic acid content (a major component of the lipid A moiety) of endotoxin after hydrolysis by selected ion-monitoring gas chromatography-mass spectrometry. More than 80% of the endotoxin was bound to hydroxylapatite, polystyrene, Dowex 1-X2, and charcoal. The binding of endotoxin to these materials was markedly reduced by the addition of normal or delipidated serum. Phenyl- and octyl-Sepharose bound 56 and 50% of the endotoxin from saline solutions, respectively. Their percent binding was increased significantly in 1 M ammonium sulfate solutions, indicating hydrophobic interactions between endotoxin and phenyl- and octyl-Sepharose. Only 5% of the endotoxin was bound to plastic polymer PSI-HAP-100 beads, and no binding was observed with concanavalin A- and heparin-Sepharose. Study of the in vitro binding of endotoxin to the above material in the presence of serum suggests that the use of these materials in removing circulating endotoxin in vivo is limited.

Gonadal Response to Testosterone Propionate during Breeding and Post-Breeding Phases in the Male Blossom-Headed Parakeet, Psittacula cyanocephala (Aves: Psittaciformes)

Testosterone propionate (1 mg per 100 g body weight per day) was administered for 15 days, by injection into the pectoral muscles, to male blossomheaded parakeets during both the spermatogenetically active (February-March) and resting (August) phases of the annual cycle. It caused marked testicular atrophy when it was injected in the sexually active birds. In sexually regressed parakeets it resulted in spermatokinesis and differentiation of Leydig cells. It is evident that the same amount of exogenous testosterone may exert, possibly through pituitary gonadotrophic agent(s), either pro- or anti-gonadal influences depending upon the sexual status of the bird.

Comparison of human urine gastric inhibitor (HUGI) and bacterial endotoxin as inhibitors of acid secretion

In conscious cats with gastric fistulas, 10 micrograms . kg-1 of human urinary gastric inhibitor (HUGI) given as an intravenous bolus injection increased mean rectal temperature 1.4 degree C and inhibited mean gastrin-stimulated acid secretion by 64%. The sample of HUGI contained an amount of beta-hydroxymyristic acid corresponding to a 5% contamination of the HUGI with bacterial endotoxin. Injection of bacterial endotoxin in an amount corresponding to the beta-hydroxymyritic acid content of HUGI mimicked, both in magnitude and time course, the increase in body temperature and the inhibition of acid secretion produced by HUGI. We conclude that inhibition of acid secretion by HUGI may be due to the presence of an endotoxin-like contaminant.

High-pressure liquid chromatography for quantitation of antimicrobial agents

Several methods are currently available for quantitation of antimicrobial drugs in serum and body fluids, e.g., microbiological, radioenzymatic, and radioimmune assays. Recently, high-pressure liquid chromatography (HPLC) has been implemented for quantitation of a variety of drugs, including antimicrobial drugs. The general principles of chromatography, particularly in reference to HPLC, are reviewed. The methods and procedures for extraction, separation, detection, and quantitation of antimicrobial drugs by HPLC are discussed. Current HPLC techniques for measuring antimicrobial drugs in biological fluids are also summarized.

Determination of aminoglycoside antibiotics in biological fluids: a review

We describe current procedures for measuring aminoglycoside antibiotics. Although many of these techniques are suitable for clinical adaptation, selection of a method for use in a clinical laboratory will depend on the budget and availability of equipment and expertise.

Determination of aminoglycoside antibiotics in biological fluids: a review

We describe current procedures for measuring aminoglycoside antibiotics. Although many of these techniques are suitable for clinical adaptation, selection of a method for use in a clinical laboratory will depend on the budget and availability of equipment and expertise.

Quantitation of serum tobramycin concentration using high-pressure liquid chromatography

A high-pressure liquid chromatography method for the quantitative determination of tobramycin in serum is described. The antibiotic was separated from serum by chromatography on a silica gel column. The adsorbed antibiotic was derivatized with o-phthalaldehyde, and then eluted with isopropanol. The derivatized tobramycin was separated by reverse-phase chromatography and quantitated by fluorometry. Serum concentrations as low as 0.5 microgram/ml could be accurately measured. A linear response for serum samples containing tobramycin ranging from 0 to 20 microgram/ml was obtained. Other antibiotics, including various aminoglycosides, did not interfere with the tobramycin assay. Comparison with a standard microbiologic assay gave a correlation coefficient of 0.99. This chemical assay is sensitive, precise, specific, and can be performed in 30 minutes.

Amikacin assay in serum by high-performance liquid chromatography

A high-performance liquid chromatographic method for the quantitative determination of amikacin in serum is described. The antibiotic was separated from serum by adsorption on silica gel. The adsorbed drug was then derivatized with o-phthalaldehyde and eluted with ethanol. The derivatized amikacin was separated by reverse-phase, high-performance liquid chromatography and quantitated by fluorometry. A linear response for serum samples containing amikacin ranging from 1.0 to 15 mug/ml was obtained. Other antibiotics including various aminoglycosides did not interfere with the amikacin assay. Comparison with a standard microbiological assay gave a correlation coefficient of 0.99. This chemical assay is sensitive and specific under the conditions tested and can be performed rapidly.

Serum gentamicin assay by high-performance liquid chromatography

We describe a high-performance liquid chromatographic method for the quantitative determination of gentamicin in serum. The antibiotic was separated from serum by passage through a silicic acid column, derivatized with o-phthalaldehyde, and eluted with ethanol. The derivatized gentamicin was then separated into all three of its major components by reversed-phase chromatography and quantified by fluorometry. Concentrations in serum as low as 0.5 mg of gentamicin per liter could be accurately determined. A standard curve showed a linear response for serum containing gentamicin at concentrations ranging from 0 to 20 mg/liter. Tobramycin, amikacin, ampicillin, penicillin G, methicillin, carbenicillin, chloramphenicol, clindamycin, and cephalothin did not interfere with the gentamicin assay. Comparison with an accepted microbiological assay yielded a correlation coefficient of 0.99. This chemical assay is rapid (less than 30 min), sensitive, accurate, specific, and appears to be applicable to other aminoglycosides.

Serum gentamicin assay by high-performance liquid chromatography

We describe a high-performance liquid chromatographic method for the quantitative determination of gentamicin in serum. The antibiotic was separated from serum by passage through a silicic acid column, derivatized with o-phthalaldehyde, and eluted with ethanol. The derivatized gentamicin was then separated into all three of its major components by reversed-phase chromatography and quantified by fluorometry. Concentrations in serum as low as 0.5 mg of gentamicin per liter could be accurately determined. A standard curve showed a linear response for serum containing gentamicin at concentrations ranging from 0 to 20 mg/liter. Tobramycin, amikacin, ampicillin, penicillin G, methicillin, carbenicillin, chloramphenicol, clindamycin, and cephalothin did not interfere with the gentamicin assay. Comparison with an accepted microbiological assay yielded a correlation coefficient of 0.99. This chemical assay is rapid (less than 30 min), sensitive, accurate, specific, and appears to be applicable to other aminoglycosides.

Heterogeneity and refined structtures of 3-O-methyl-D-mannose polysaccharides from Mycobacterium smegmatis

The 3-O-methyl-D-mannose-containing polysaccharide (MMP) from Mycobacterium smegmatis, first described by Gray and Ballou (Gray, G. R., and Ballou, C. E. (1971) J. Biol. Chem. 246, 6835-6842) is now shown to be a mixture of at least four isomers separable by gel filtration owing to differences in size and degree of methylation. The major component is 3-O-methylmannose but all contain small amounts of mannose. The molecular weights range from 2040 to 2490 and all are nonreducing. After Smith degradation, all yield a single large and one or more small fragments that give 3-O-methylmannose as the sole product of complete acid hydrolysis. The large Smith-degraded MMP components (SD-MMP) are similar to intact MMP and vary from 1830 to 2130 daltons, consistent with the loss of a single mannose; whereas the smaller fragments are the size of tri- to hexasaccharides and result from fragmentation of incompletely methylated chains. Controlled acid hydrolysis of [methyl-3H]MMP releases 6% of the methyl groups as [3H]methanol at a rate characteristic for the hydrolysis of methyl alpha-D-mannopyranoside. Proton magnetic resonance spectra of MMP and SD-MMP show a major methyl ether proton peak and a second small peak at higher field equivalent to about one methyl group per molecule. The results are consistent with the presence of an alpha-methyl aglycon at the reducing end of the chains. Methylation analysis of MMP isomers purified by high pressure liquid chromatography confirms that they are linear and unbranched. Methylation of [methyl-3H]MMP yields unlabeled tetra-O-methylmannose, showing that the chains are terminated by mannose. However, digestion of [methyl-3H]MMP with alpha-mannosidase releases mannose and exposes [methyl-3H]3-O-methylmannose. Smith degradation of [methyl-3H]MMP III yields a penta-to hexasaccharide product that can be resolved by high pressure liquid chromatography into two components. The distribution of radioactivity between these two fragments suggests that the chain was cleaved near the middle and that there must be an unmethylated mannose at that position. We conclude that the 3-O-methylmannose polysaccharides are linear unbranched chains of 11 to 14 sugar units, each terminated by a single mannose at the nonreducing end and by a methyl aglycon at the reducing end. Each isomer shows microheterogeneity, with 1 or 2 unmethylated mannose units near the middle of some but not all of the chains.

An endo-alpha1 leads to 6-D-mannanase from a soil bacterium. Purification, properties, and mode of action

A soil organism, isolated by enrichment culture on unbranched alpha1 leads to 6-mannan backbone from the yeast Saccharomyces cerevisiae, secretes and endo-alpha1 leads to 6-mannanase. We have purified this mannanase to homogeneity and find it to consist of a single polypeptide chain with a molecular weight of about 131,000. The enzyme is unusually heat-stable and appears to be highly extended in shape, possessing very little alpha helicity but with a high proportion of beta structure. The mannanase acts on unbranched alpha1 leads to 6-mannan to produce mannose and alpha1 leads to 6-mannobiose, with the intermediate formation of alpha1 leads to 6-mannooligosaccharides of various sizes. Calcium ion is required for full activity. The smallest substrate is the alpha1 leads to 6-mannotriose, whereas the reduced mannotriose is an inhibitor. The combining site appears to encompass 6 to 8 mannose units.

Histological, histochemical and biochemical effects of cadmium chloride in female koel (Eudynamys scolopacea)

Effects of single subcutaneous injection (1.5 mg/100 g body weight) of cadmium chloride were studied in the ovary, oviduct, thyroid and adrenal gland of Indian koel (Eudynamys scolopacea). Treatment resulted the significant decrease (p less than 0.001) in the weight of ovary and oviduct. The stromal tissue showed hyperaemia and profused haemorrhage leading to some cellular destruction. A marked degeneration was noticed in the lamina propria of magnum. No remarkable change occured in thyroid histology. An increment of alkaline phosphatase activity was pronounced in ovarian tissue as well as in magnum after the injection. An overall reduction of periodic acid Schiff reaction was noticed in both ovary and oviduct after the salt treatment. The experiment caused a significant reduction of eponephrine content (p less than 0.001) in hypertrophied adrenal medulla. The cortical tissues, however, unaltered in their histomorphology. The loss of total amount of cholesterol (p less than 0.05) from the adrenal gland after the experimentation was recorded. It has been suggested that the augmentation of epinephrine secretion suppressed the gonadal acitivty.