Tumor-specific cholinergic CD4+ T lymphocytes guide immunosurveillance of hepatocellular carcinoma

Cholinergic nerves are involved in tumor progression and dissemination. In contrast to other visceral tissues, cholinergic innervation in the hepatic parenchyma is poorly detected. It remains unclear whether there is any form of cholinergic regulation of liver cancer. Here, we show that cholinergic T cells curtail the development of liver cancer by supporting antitumor immune responses. In a mouse multihit model of hepatocellular carcinoma (HCC), we observed activation of the adaptive immune response and induction of two populations of CD4+ T cells expressing choline acetyltransferase (ChAT), including regulatory T cells and dysfunctional PD-1+ T cells. Tumor antigens drove the clonal expansion of these cholinergic T cells in HCC. Genetic ablation of Chat in T cells led to an increased prevalence of preneoplastic cells and exacerbated liver cancer due to compromised antitumor immunity. Mechanistically, the cholinergic activity intrinsic in T cells constrained Ca2+-NFAT signaling induced by T cell antigen receptor engagement. Without this cholinergic modulation, hyperactivated CD25+ T regulatory cells and dysregulated PD-1+ T cells impaired HCC immunosurveillance. Our results unveil a previously unappreciated role for cholinergic T cells in liver cancer immunobiology.

Identification of an Optimized Receptor-Binding Domain Subunit Vaccine against SARS-CoV-2

Current vaccine efforts to combat SARS-CoV-2 are focused on the whole spike protein administered as mRNA, viral vector, or protein subunit. However, the SARS-CoV-2 receptor-binding domain (RBD) is the immunodominant portion of the spike protein, accounting for 90% of serum neutralizing activity. In this study, we constructed several versions of RBD and together with aluminum hydroxide or DDA (dimethyldioctadecylammonium bromide)/TDB (d-(+)-trehalose 6,6'-dibehenate) adjuvant evaluated immunogenicity in mice. We generated human angiotensin-converting enzyme 2 knock-in mice to evaluate vaccine efficacy in vivo following viral challenge. We found that 1) subdomain (SD)1 was essential for the RBD to elicit maximal immunogenicity; 2) RBDSD1 produced in mammalian HEK cells elicited better immunogenicity than did protein produced in insect or yeast cells; 3) RBDSD1 combined with the CD4 Th1 adjuvant DDA/TDB produced higher neutralizing Ab responses and stronger CD4 T cell responses than did aluminum hydroxide; 4) addition of monomeric human Fc receptor to RBDSD1 (RBDSD1Fc) significantly enhanced immunogenicity and neutralizing Ab titers; 5) the Beta version of RBDSD1Fc provided a broad range of cross-neutralization to multiple antigenic variants of concern, including Omicron; and 6) the Beta version of RBDSD1Fc with DDA/TDB provided complete protection against virus challenge in the knock-in mouse model. Thus, we have identified an optimized RBD-based subunit vaccine suitable for clinical trials.

IDH2 and TET2 mutations synergize to modulate T Follicular Helper cell functional interaction with the AITL microenvironment

Angioimmunoblastic T cell lymphoma (AITL) is a peripheral T cell lymphoma that originates from T follicular helper (Tfh) cells and exhibits a prominent tumor microenvironment (TME). IDH2 and TET2 mutations co-occur frequently in AITL, but their contribution to tumorigenesis is poorly understood. We developed an AITL mouse model that is driven by Idh2 and Tet2 mutations. Malignant Tfh cells display aberrant transcriptomic and epigenetic programs that impair TCR signaling. Neoplastic Tfh cells bearing combined Idh2 and Tet2 mutations show altered cross-talk with germinal center B cells that promotes B cell clonal expansion while decreasing Fas-FasL interaction and reducing B cell apoptosis. The plasma cell count and angiogenesis are also increased in the Idh2-mutated tumors, implying a major relationship between Idh2 mutation and the characteristic AITL TME. Our mouse model recapitulates several features of human IDH2-mutated AITL and provides a rationale for exploring therapeutic targeting of Tfh-TME cross-talk for AITL patients.

Distinct and opposite effects of leukemogenic Idh and Tet2 mutations in hematopoietic stem and progenitor cells

Mutations in IDH1, IDH2, and TET2 are recurrently observed in myeloid neoplasms. IDH1 and IDH2 encode isocitrate dehydrogenase isoforms, which normally catalyze the conversion of isocitrate to α-ketoglutarate (α-KG). Oncogenic IDH1/2 mutations confer neomorphic activity, leading to the production of D-2-hydroxyglutarate (D-2-HG), a potent inhibitor of α-KG-dependent enzymes which include the TET methylcytosine dioxygenases. Given their mutual exclusivity in myeloid neoplasms, IDH1, IDH2, and TET2 mutations may converge on a common oncogenic mechanism. Contrary to this expectation, we observed that they have distinct, and even opposite, effects on hematopoietic stem and progenitor cells in genetically engineered mice. Epigenetic and single-cell transcriptomic analyses revealed that Idh2^R172K and Tet2 loss-of-function have divergent consequences on the expression and activity of key hematopoietic and leukemogenic regulators. Notably, chromatin accessibility and transcriptional deregulation in Idh2^R172K cells were partially disconnected from DNA methylation alterations. These results highlight unanticipated divergent effects of IDH1/2 and TET2 mutations, providing support for the optimization of genotype-specific therapies.

Concerted roles of PTEN and ATM in controlling hematopoietic stem cell fitness and dormancy

In order to sustain proficient life-long hematopoiesis, hematopoietic stem cells (HSCs) must possess robust mechanisms to preserve their quiescence and genome integrity. DNA-damaging stress can perturb HSC homeostasis by affecting their survival, self-renewal, and differentiation. Ablation of the kinase ataxia telangiectasia mutated (ATM), a master regulator of the DNA damage response, impairs HSC fitness. Paradoxically, we show here that loss of a single allele of Atm enhances HSC functionality in mice. To explain this observation, we explored a possible link between ATM and the tumor suppressor phosphatase and tensin homolog (PTEN), which also regulates HSC function. We generated and analyzed a knockin mouse line (PtenS398A/S398A), in which PTEN cannot be phosphorylated by ATM. Similar to Atm+/-, PtenS398A/S398A HSCs have enhanced hematopoietic reconstitution ability, accompanied by resistance to apoptosis induced by genotoxic stress. Single-cell transcriptomic analyses and functional assays revealed that dormant PtenS398A/S398A HSCs aberrantly tolerate elevated mitochondrial activity and the accumulation of reactive oxygen species, which are normally associated with HSC priming for self-renewal or differentiation. Our results unveil a molecular connection between ATM and PTEN, which couples the response to genotoxic stress and dormancy in HSCs.

0066 Glycinergic Postsynaptic Inhibition is Responsible for the Suppression of Hypoglossal Motoneuron Activity During Naturally-Occurring REM Sleep

Introduction

The present study was undertaken to explore the role of glycinergic postsynaptic inhibition and monoaminergic disfacilitation (a withdrawal of excitatory noradrenergic and serotonergic inputs) in the control of hypoglossal motoneuron activity during REM sleep. Accordingly, glycinergic, noradrenergic and serotonergic antagonists were microinjected into the hypoglossal nucleus, and their effects on the hypoglossal nerve activity during REM sleep were examined in chronically-instrumented, unanesthetized cats.

Methods

Adults cats were prepared for monitoring behavioral states of sleep and wakefulness, and for extracellular recordings from hypoglossal nerve. Strychnine (a glycinergic antagonist) and a mixture of prazosin (a noradrenergic antagonist) and methysergide (a serotonergic antagonist) were microinjected, separately, into the hypoglossal nucleus during naturally-occurring states of sleep and wakefulness.

Results

During REM sleep, compared to non-REM sleep, the hypoglossal nerve activity decreased by 17.4±1.5% (n=17) in the control recordings (prior to the injection of strychnine). Following the microinjection of strychnine, there was only a mean decrease of 7.2±1.2% (n=12) in the nerve activity during REM sleep versus NREM sleep. The strychnine effect was statistically significant compared to control (p<0.001; unpaired t-test), which indicates that strychnine blocks REM sleep-related suppression of hypoglossal nerve activity. In contrast, the microinjection of prazosin and methysergide did not significantly reduce the hypoglossal nerve activity during REM sleep (control: 15.9±2.3, n=9 vs. prazosin+methysergide: 12.6±1.4%, n=10, p=0.229, unpaired t-test).

Conclusion

The present results demonstrate that the microapplication of strychnine, but not prazosin and methysergide, into the hypoglossal nucleus significantly reduces the suppression of the hypoglossal nerve activity during naturally-occurring REM sleep. We therefore suggest that glycinergic postsynaptic inhibition is primarily responsible for the suppression of hypoglossal motoneuron activity during REM sleep.

Support

5R01NS094062

0067 An Anatomic Substrate for GABAergic Processes to Suppress Active Sleep and Promote Wakefulness in the Nucleus Pontis Oralis

Introduction

Our previous electrophysiologic data have provided compelling evidence that GABAergic processes in the nucleus pontis oralis (NPO) play a critical role in the generation and maintenance of wakefulness as well as active (REM) sleep (AS). We therefore hypothesized that one of the neuronal mechanisms of GABA actions in the NPO to promote wakefulness and suppress AS is due to a direct GABAergic inhibition of NPO neurons that generate AS (AS-generator neurons). However, the anatomical substrate for this inhibition is undetermined. Accordingly, the present study was undertaken to examine whether there is any direct interaction between GABAergic neurons and glutamatergic AS-generator neurons in the NPO.

Methods

Adult cats were deeply anesthetized and perfused transcardially. The brainstem containing the NPO was removed, postfixed and cut into 15 μm coronal sections with a Reichert-Jung cryostat. The sections were incubated with a mixture of a rabbit polyclonal antibodies against glutamine and GABA following the procedure of double fluorescence immunohistochemistry.

Results

There was a large number of neuronal somata labeled by anti-glutamine antibody and terminals labeled by anti-GABA antibody in the NPO. These glutamine-positive neurons were medium to large, multipolar cells (> 20 μm), which resemble glutamatergic, AS-generator neurons that have been previously identified in the NPO. Specifically, majority of glutamatergic neuronal somata were closely apposed by multiple GABAergic terminals, indicating that AS-generator neurons in the NPO receive direct GABAergic inputs.

Conclusion

The present results demonstrate that a direct connection exists between glutamatergic AS-generator neurons and GABAergic processes in the NPO. These data provide the anatomical evidence which supports our hypothesis that the pontine GABAergic control of wakefulness and active sleep is partially mediated via GABAergic processes project to NPO AS-generator neurons that suppress the activity of these cells.

Support

NS092383

Psychological and Neurobiological Correlates of Food Addiction

Food addiction (FA) is loosely defined as hedonic eating behavior involving the consumption of highly palatable foods (ie, foods high in salt, fat, and sugar) in quantities beyond homeostatic energy requirements. FA shares some common symptomology with other pathological eating disorders, such as binge eating. Current theories suggest that FA shares both behavioral similarities and overlapping neural correlates to other substance addictions. Although preliminary, neuroimaging studies in response to food cues and the consumption of highly palatable food in individuals with FA compared to healthy controls have shown differing activation patterns and connectivity in brain reward circuits including regions such as the striatum, amygdala, orbitofrontal cortex, insula, and nucleus accumbens. Additional effects have been noted in the hypothalamus, a brain area responsible for regulating eating behaviors and peripheral satiety networks. FA is highly impacted by impulsivity and mood. Chronic stress can negatively affect hypothalamic-pituitary-adrenal axis functioning, thus influencing eating behavior and increasing desirability of highly palatable foods. Future work will require clearly defining FA as a distinct diagnosis from other eating disorders.

Effects of adrenal medulla graft on recovery of GABAergic and dopaminergic neuron deficits in mice: behavioural, pharmacological and immunohistochemical study

We studied the capacity of adrenal medullary transplant to restore the deficits of GABAergic and dopaminergic neurons in mice injected with quinolinic acid (QA), using an open field test as well as pharmacological and immunohistochemical techniques. We analysed behavioural traits-total locomotor activity, peripheral and central activities, grooming, leaning and rearing in the QA-lesioned mice and mice that had undergone adrenal medulla (AM) transplantation. We found that the adrenal transplant recovered a loss of GABAergic neurons. It reduced QA-induced hyperactivity in locomotion and improved emotional indices. In addition, immunohistochemical studies of catecholaminergic markers-tyrosine hydroxylase (TH), dopamine (DA) and neuronal vesicular monoamine transporter type 2- and a single post-trial injection of tetrabenazine (TBZ; 5 mg/kg) indicated that catecholamines-synthesising chromaffin cells in the AM grafts were also involved in the beneficial effects. A likely interpretation of this behavioural pattern of results is that adrenal medullary transplants set into play an interaction between GABAergic and DAergic factors. Our results may contribute to the clarification of the beneficial effects of AM transplants in striatal function.

Chlamydia trachomatis: opportunistic screening in primary care

Following the publication of the Chief Medical Officer's report on chlamydial screening, we identified the sexual health of young women as an area for concern. As part of our review we decided to opportunistically search for chlamydial genital infections using a non-invasive technique. Sexually active women under 25 years of age were invited to submit a first void urine sample for polymerase chain reaction analysis. Over the period of a year we found out that 10.9% of sexually active young women tested positive for chlamydia in our practice.

Involvement of adrenal medulla grafts in the open field behavior

Immunohistochemical and behavioral techniques were used to study the effects of adrenal medulla grafts, implanted in striatum after bilateral kainic acid (KA) lesions of this structure, on the open field behavior of mice. KA-induced behavioral changes in leaning, grooming and locomotor activity of the open field test were significantly improved after grafting of the adrenal medulla, and in some respects, fully restored. Immunohistochemical identification showed that grafts contained neuron-like cells with a tyrosine hydroxylase (TH), phenylethanolamine N-methyltransferase, gamma-aminobutyric acid (GABA), choline acetyltransferase (ChAT), and enkephalin-like immunostainings. A likely interpretation of this complex pattern of results is that adrenal medullary grafts may restore the deficits of GABAergic neurons which in turn reverse the abnormalities in emotionality and locomotion. Neurobiologically, these behavioral improvements probably involve GABAergic and catecholaminergic factors of adrenal medulla grafts, although other neuroactive substances, such as acetylcholine and enkephalins, cannot be excluded.

Testosterone treatment results in quiescent satellite cells being activated and recruited into cell cycle in rat levator ani muscle

At puberty, the male levator ani (LA) muscle exhibits muscle fiber hypertrophy. This fiber enlargement can be provoked in the female LA muscle by testosterone treatment. In both cases the hypertrophic process is accompanied by an increase in the number of satellite cells and myonuclei. The present ultrastructural autoradiographic study was undertaken in order to investigate (1) whether satellite cells when stimulated by testosterone can undergo DNA synthesis by incorporating [3H]thymidine ([3H]Tdr); (2) whether the whole satellite cell population is committed in the cell cycle; and (3) whether the new myonuclei originate from fusion of the satellite cells with the preexistant myofibers. Thirty-day-old female rats treated with a single testosterone injection received a single injection of [3H]Tdr at 24, 28, 32, to 34 hr after testosterone treatment. LA muscles were removed 2 hr after [3H]Tdr injection. This first series of experiments allowed us to determine that onset of DNA synthesis in satellite cells occurs within the 34th and the 36th hour after testosterone treatment. To obtain a more precise timing, 30-day-old female rats treated with a single testosterone injection received multiple injections every 30 min either from Hour 32 to 33.5 or from Hour 34 to 35.5 LA muscles were removed 30 min after the last [3H]Tdr injection. This showed that the onset of satellite cell replication occurred between the 32nd and the 34th hour after testosterone treatment. However, only 30% of the satellite cell population was affected by this proliferative process regardless of the experimental protocol used. To confirm that the increase in myonuclei number results from incorporation of satellite cells into mature myofibers, 30-day-old female rats treated with a single injection of testosterone received a single injection of [3H]Tdr on the 60th hour after testosterone treatment. LA muscles were removed at 63, 84, to 108 hr after [3H]Tdr injection. We conclude that testosterone induces satellite cell proliferation at around the 33rd hour and that the increased number of myonuclei reported in our previous study is due to fusion of labeled satellite cells with myofibers.

Testosterone-induced masculinization of the rat levator ani muscle during puberty

Previous study of the development of the levator ani muscle (LA) revealed that the sex difference in muscle fiber number is under the control of testosterone during the perinatal period. In this study, the development of the LA muscle was examined in both sexes to test the hypothesis that testosterone action determines a further sex difference at the onset of puberty. This period is of key importance because plasma testosterone concentration rises sharply between Postnatal Days 40 and 60 in the male, while in the female testosterone level stays very low. In the male, a transient increase in the satellite cell number occurs between Days 42 and 47, followed by a persistent myonuclei increase. Hence, when the pubertal process has been completed, the myonuclei number is increased by about 50%. Moreover, sexual dimorphism related to the muscle fiber width becomes more marked: before puberty (Day 30), the mean cross-sectional area of muscle fibers is 2-fold higher in males than in females, while between Days 30 and 78, a further hypertrophy is observed which leads to a mean cross-sectional area about 10-fold higher in the male. In the female, during the same period, there is neither satellite cell increase nor myonuclei increase and the fiber cross-sectional area remains constant. Treatment with testosterone before the onset of puberty induces a marked but transient satellite cell increase not only in male but also in female LA muscle as early as 3 days after the time of injection. This cell proliferation is followed by a subsequent increase in the myonuclei number. Results indicate that (1) the levator ani muscle in the male exhibits high sensitivity to testosterone during the pubertal process; during this period, sexual dimorphism related to fiber width and myonuclei number is emphasized; (2) the myonuclei increase is subsequent to the testosterone-induced satellite cell proliferation; and (3) the female LA muscle presents the same sensitivity to testosterone as the male. Hence, the female muscle does not acquire specific male characteristics, owing to the very low concentration of circulating androgens.

Holding their own with pediatric hospice

Hospice is an excellent realm of care for helping pediatric patients and their families through the tragedy of life cut short. The commitment in time and resources is great but, as the experience of one agency has shown, a special program for pediatric hospice care can serve an entire community.

Characterization of a rapid and sensitive enzyme immunoassay (EIA) for progesterone applied to conditioned cell culture media

Progesterone accumulation in conditioned media is a frequently employed endpoint for in vitro cell culture of steroidogenic cells. Although radioimmunoassay (RIA) has been the predominant method for measurement of progesterone, a number of nonradiometric immunoassays have been described but they have not been applied to conditioned media. Here, we report the characterization of a microtitre plate enzyme immunoassay (EIA) for determination of progesterone in conditioned media. The EIA has a sensitivity of 0.3 pg per well with intraassay and interassay coefficients of variation of 7.3 and 10.2%, respectively. The specificity of the EIA is no different than that of a comparable RIA showing crossreactivities of less than 0.1% for other steroids except 5 alpha-pregnan-3,20-dione (47%) and 11 alpha-hydroxyprogesterone (18%). Progesterone levels from conditioned cell culture media of either rat or human granulosa cell cultures measured by both EIA and RIA were in close agreement (r = 0.96) and serial dilutions of culture samples in the EIA were parallel to those of the standards. Also, extraction of culture media prior to EIA was found not to be necessary. Thus, this EIA is a highly sensitive and specific assay that provides a rapid, simple, inexpensive, and non-radiometric alternative to radioimmunoassay for measurement of progesterone in conditioned cell culture media.

Effect of testosterone and thyroid hormone on the expression of myosin in the sexually dimorphic levator ani muscle of rat

During postnatal development, the myosin transition from embryonic and neonatal isoforms to adult isoforms has been shown to occur with half-transition times of about 20 and 32 days in the male and female levator ani muscles, respectively. We show that this difference could not be attributed to the testosterone male hormone, since treatment of newborn females by testosterone did not modify the half-transition time. However, treatment of females by thyroid hormone accelerated the myosin transition of the female muscle, which then occurred at almost the same time as the transition of the male muscle. This suggests that the difference between the half-transition times of the male and female levator ani muscles may be largely attributed to different sensitivities of the male and female muscles to thyroid hormone. This is the first example of sexually dimorphic muscle response to thyroid hormone.

Testosterone-induced development of the rat levator ani muscle

The perinatal development of the levator ani (LA) muscle in male and female rats was investigated by measuring the total number of muscle units (MU) (i.e., mononucleate cells, clustered or independent myotubes, and muscle fibers) in transverse semithin sections of the entire muscle and the MU cross-sectional area in 22-day-old fetuses (F22), 1-day-old (D1 = day of birth), 3-day-old (D3), and 6-day-old (D6) newborns. Male muscle contained 350 +/- 64 MU on F22, twice that of the female. The number of MU increased markedly in males from F22, but changed little in females; the number of MU in males was 760% that of females on D6. The MU cross-sectional area was greater in males on F22 (120.8 micron(s)2 +/- 7.5) and D1 (155.2 micron(s)2 +/- 64.8) than in females (F22: 89.2 micron(s) +/- 14.2, D1: 64.1 micron(s)2 +/- 19.7) and dropped to about 30 X micron(s)2 in both sexes on D6. Female rats given a single injection of testosterone propionate (TP) before D7 showed a significant increase in the number of fibers, but no increase in cross-sectional area. TP given after D7 had no effect on the fiber number, but increased the average cross-sectional area. The increase in fiber number induced by postnatal TP treatment was a permanent effect, still quantifiable in 15-month-old females. We conclude that the sexual dimorphism of the rat LA muscle is principally due to a dramatic increase in the MU number in male muscles during the perinatal period, rather than to involution of the fibers in female muscles as it is widely accepted. This increase seems to be, at least partly, under the control of testosterone.

Satellite cell proliferation and increase in the number of myonuclei induced by testosterone in the levator ani muscle of the adult female rat

We injected adult female rats with 0.25 mg/100 g body weight of testosterone to test the sensitivity to androgens of the levator ani muscle (LAM). Testosterone induced marked hypertrophy characterized by fiber size enlargement, but did not increase the number of fibers. Morphological observations and quantitative data indicated that hypertrophy was accompanied by satellite cell proliferation between Days 1 and 3 after testosterone treatment, and by an increase in the number of myonuclei, which started between Days 2 and 3 after treatment. On Day 30, this increase reached 80% of the initial number of myonuclei. The new myonuclei seemed to result from satellite cell proliferation and from the fusion of some of them with preexistent muscle fibers. These results strongly suggest that testosterone-induced cell proliferation might have a role in developing the sexual dimorphism of the LAM. They also indicate the need to reconsider the currently accepted notion that sexual dimorphism is owing to female LAM involution.

Cone adaptation in age-related maculopathy

Cone adaptation was measured in patients with age-related maculopathy (ARM) and age-matched controls. A red stimulus was used to selectively bias responses toward cone function and adaptation was measured 5, 10, 20, and 40 degrees eccentric to fixation. The ARM patients' thresholds were elevated by 1 log unit at 5 and 10 degrees, with the threshold difference reducing to 0.5 log units at 40 degrees. Curves of the form log (threshold luminance) = ae-bt + c (where t is time and a, b, and c are constants) were fitted to each adaptation curve; a procedure involving differentiation of the above equation was used to estimate the constant parameters. Time constants of cone recovery (1/b) were derived for each fitted curve. No significant difference was found between the time constants of the two test groups. Our data suggest that cone adaptation is significantly affected in patients with ARM, with raised cone thresholds occurring for areas well into the peripheral retina. We suggest that the effect is mediated by a reduction in the number of functional cones, which elevates the final cone thresholds without altering the adaptation time constant. Our findings imply that age-related "maculopathy" may not be confined to the macular area, and that early signs of the degeneration may be present in the peripheral retina even when central acuity is normal.

Evaluation of a pectin-based barrier under tape to protect neonatal skin

The use of a pectin-based barrier between tape and skin as a method of minimizing epidermal stripping while keeping monitoring equipment and other devices securely attached to infants was evaluated. From 45 subjects, 199 application/removal procedures were recorded. The pectin-based barrier under tape held appliances securely for an average of 5.5 days (range 1-23 days). In 72% of the observations, the barrier was removed for nonadhesive-related reasons. Skin condition remained grossly normal in 97% of the observations after the barrier removal. A pectin-based barrier under tape provides effective adhesion for certain appliances and protects neonatal skin from damage caused by tape removal.

Effect of castration on the morphology of the motor end-plates of the rat levator ani muscle

The levator ani (L. A.) muscle, part of the genital apparatus of rodents, atrophies after castration. Changes in end-plate structure in the L. A. muscle of castrated male rats were examined with correlated light and electron microscopic methods. Four months after castration acetylcholinesterase staining reveals, in some muscle fibres, the presence of subneural gutters composed of a succession of cuplets whereas the subneural gutters are continuous and ramified in control muscles. Six months after castration most of the end-plates are further modified. Their terminal arborization, as revealed by silver nitrate staining, is more tortuous and irregular than in controls. At the ultrastructural level, reduced sole-plate and superimposed axonal endings are seen in some end-plates three months after castration. Our findings demonstrate that the changes (reduction of muscular activity and atrophy of muscle) are accompanied by adaptations of the neuromuscular junctions. As receptors for testosterone are known to be present in these motoneurons and muscle fibres, the observed morphological changes might be under the control of testosterone acting on both muscle and motoneurons.

Vowel and nasal duration as cues to voicing in word-final stop consonants: spectrographic and perceptual studies

To determine durational differences between vowel and nasal segments preceding word-final /t/ and /d/, spectrograms were made of adult speakers' productions of minimal pairs of the type /pent/-/pend/. Vowel, nasal, and vowel plus nasal (vocalic nucleus) durations were greater before /d/ than before /t/. Assuming the voiceless context as a base, the increase in nasal duration in the voiced case was proportionately greater than the increase in vowel duration. This outcome suggests that nasal duration is a more powerful cue to the voicing characteristic of the following consonant than is vowel duration. To test this, adult listeners were presented synthetic CVNC utterances in which the nasal and vowel segments were independently varied in duration over a range of 40 msec to 200 msec and were instructed to label the final stop consonant as either voiced /d/ or voiceless /t/. Although changes in both vowel and nasal duration were sufficient to cue both voiced and voiceless judgements, listeners' categorization of final consonants shifted more rapidly as a result of varying nasal rather than vowel duration. Nasal duration, therefore, appears to be a stronger cue than vowel duration for the word-final voiced-voiceless consonant distinction in CVNC utterances.