The interdural hematoma: A subtype of convexity subdural/dural hematoma with specific radioanatomical characteristics

Background

Rare cases of biconvex hematomas splitting the convexity dura mater were reported and denominated interdural hematoma (IDH). Due to their rarity, little is known about their radiological characteristics, and in most cases, their invasive management with craniotomy and dural membrane excision is unnecessary.

Case Description

We report here a case of single burr-hole endoscopic evacuation of an IDH and its complete resolution after the 6-month follow-up imaging. The literature review reveals 11 reported cases of IDH. Most of them are male and the mean age is 65 years (range 51-90). Most of the reported IDHs were misdiagnosed as epidural hematoma or meningioma, and therefore, they have been managed invasively through craniotomy with dural excision. Diagnosis of the interdural nature was confirmed macroscopically during surgery in all cases and histology was reported for 6 cases. Image analysis found a double dural beak sign and biconvex shape on coronal planes, subarachnoid space enlargement at the collection extremities, and irregular thick inner wall as common radiological aspects of the IDH.

Conclusion

IDH is a rarely reported and often misdiagnosed dural hematoma subtype. Its invasive treatment through craniotomy is likely related to its unknown radiological characteristics. We review and raise awareness about potentially unique radiological anatomy that could avoid unnecessary invasive treatment. Moreover, we report the first case of endoscopically evacuated IDH with long-term follow-up imaging showing complete resolution.

Intravenous leiomyomatosis: Case series and review of the literature

Introduction

Intravenous leiomyomatosis (ILV) is a rare pathology, part of leiomyoma beyond the uterus (LBU), characterized by benign smooth muscle cell tumor outside of the uterus and mainly affecting premenopausal woman with a medical history of leiomyoma or gynecologic surgical treatment. The treatment depends on the localization of the tumor, age of the patient, initial size, symptoms and the suitability for surgery but should always aims in toto surgical resection.

Case presentation

Retrospective case series and review of literature.

Clinical discussion

Symptoms presented by the patient were aspecific and only localized in the pelvic area. All cases were fortuitous histopathological diagnosis. No relapse was. Two out of 5 patients have pulmonary nodules, only one was biopsied and diagnosed with PBML (pulmonary benign metastasizing leiomyoma).

Conclusion

IVL and BML are rare disease that can co-exist. Because of tumoral hormonal receptors, hormonotherapy could be an optional treatment but to date no clear efficacy is demonstrated. In case of high recurrence risk such as voluminous initial mass, impairment of broad ligament, failure of total surgical resection, adjuvant hormonotherapy could be useful. Recurrence rate is about 16.6-30% and can occur even dozen years later and even after radical surgery, justifying a regular follow up.

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Leiomyomas beyond the uterus (LBU) is defined by benign smooth muscle cell tumor outside of the uterus. Sub classification of this entity are intravenous leiomyomatosis (IVL), benign metastasizing leiomyomas (BML), diffuse peritoneal leiomyomatosis (DPL), retroperitoneal leiomyomas and parasitic leiomyomas.

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The differential diagnosis of IVL should include benign myoma, thrombus, leiomyosarcoma, soft tissue sarcoma, lymphoma, cardiac myxoma, tumor thrombosis of Wilms tumor or metastasis.

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Treatment of IVL is usually surgery but there is no consensus about the the optimal approach. Adjuvant therapy sur as bilateral salpingoophorectomy followed by hormonothetherapy have to be balanced with their side effects.

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Despite being histologically benign, BML shows the metastatic potential of LBU.

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Because of a high rate of recurrence estimated of 16.6% to 30%, long term follow up is recommended even after radical surgery.

Study of the mortality mechanisms of yeasts in fermentation: Role of micronutrients limitations and nitrogen

Yeast cell death can occur during wine alcoholic fermentation and lead to sluggish or stuck fermentations. The mechanisms underlying cell death during yeast starvation in alcoholic fermentations remain unclear. In this work we addressed yeast cell death using conceptual framework from ageing studies showing that yeast resistance to starvation can be influenced by the nature of the nutrient limiting cell growth. We examined cell death occurrence considering yeast cells ability to elicit an appropriate response to a set of nutrient limitations. We show that several micronutrients limitations (oleic acid, ergosterol, pantothenic acid and nicotinic acid) trigger cell death in a nitrogen-dependent manner. We provide evidence that the nitrogen Tor/Sch9 signaling pathway is involved in triggering cell death. In such conditions, yeast cells fail to acquire stress resistance given a restriction at a post-transcriptional level. We have examined the ability of different nitrogen sources to trigger cell death and show that they impact differentially on cell death and that NH4 + had a strong death inducing capacity. Finally, the QTLs approaches allowed the mapping of a set of loci controlling cell death under oleic acid and pantothenic acid starvation consistent with a multigenic control.

Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia: A Case Report and Review of the Literature

Patient: Female, 69

Final Diagnosis: Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Symptoms: Occasional and mild shortness of breath • persistent nocturnal cough

Medication: —

Clinical Procedure: Surgical intervention: right middle lobectomy

Specialty: Surgery

Intramammary metastatic melanoma of unknown primary origin in a 58-year old patient: a case report

BACKGROUND

Malignant melanoma metastasis to the breast is a rare disease.

CASE PRESENTATION

We present the case of a 58-year-old postmenopausal Caucasian woman with metastatic malignant melanoma of unknown origin of the right breast. She presented with a palpable lump in the inferior quadrant of her right breast. The investigations concluded it was breast metastasis from a malignant melanoma of unknown origin. The treatment consisted of mastectomy and axillary lymph node dissection. Two lymph nodes were positive for tumor cells and one showed extracapsular extension. Our patient did not receive immediate adjuvant therapy. Six weeks after the surgery, our patient presented a relapse in the right axilla (a 6 × 4 cm mass) with positive internal mammary lymph nodes and a single brain metastasis. This relapse motivated an adjuvant treatment with partial regression of the disease. Currently, our patient presents multiple metastases with poor prognosis.

CONCLUSIONS

From this experience, we advocate an immediate aggressive handling of melanoma metastasis to the breast.

Wettability of PEDOT:PSS films

Conducting polymers such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (

PEDOT

PSS) are increasingly used to interface electronics with biology. Their wettability, however, remains poorly understood. We show that the frequently-used sessile drop technique yields results that are strongly dependent on the experimental conditions (measurement duration and relative humidity), due to the hydrogel-like behavior of

PEDOT

PSS. In contrast, the captive bubble technique on a fully wet film overcomes these limitations. Dynamic wettability measurements provide hysteresis values for this polymer and clarify the physical meaning of the static contact angles measured by sessile drop and captive bubble. Finally we show that aging the films in water leads to loss of PSS chains which makes the films more hydrophobic. The addition of a crosslinker reduces and slows down these effects.

Primary malignant achromic melanoma of the lung

Currently, less than thirty cases of primary malignant melanoma of the lung have been reported in the literature. Thus, strict criteria for diagnosis have been published and include: malignant melanoma associated with bronchial epithelial changes; a solitary lung tumor; no prior history of skin, mucous membrane, intestinal or ocular melanoma; and absence of any other detectable tumor at the time of diagnosis. In this article we present a case of melanoma of the lung without evidence of extra-pulmonary disease.

A wearable inertial system to assess the cervical spine mobility: comparison with an optoelectronic-based motion capture evaluation

In clinical settings, the cervical range of motion (ROM) is commonly used to assess cervical spine function. This study aimed at assessing cervical spine mobility based on head and thorax kinematics measured with a wearable inertial system (WS). Sequences of imposed active head movements (lateral bending, axial rotation and flexion-extension) were recorded in ten controls and 13 patients who had undergone an arthrodesis. Orientation of the head relative to the thorax was computed in terms of 3D helical angles and compared with the values obtained using an optoelectronic reference system (RS). Movement patterns from WS and RS showed excellent concurrent validity (CMC up to 1.00), but presented slight differences of bias (mean bias<2.5°) and dispersion (mean dispersion<4.2°). ROM obtained using WS also showed some differences compared to RS (mean difference<5.7°), within the range of those reported in literature. WS enabled the observation of the same significant differences between controls and patients as RS. Moreover, ROM from WS presented good test-retest repeatability (ICC between 0.63 and 0.99 and SEM<6.2°). In conclusion, WS can provide angles and ROM comparable to those obtained with RS and relevant for the cervical assessment after treatment.

Objective evaluation of cervical spine mobility after surgery during free-living activity

BACKGROUND

Evaluation of cervical spine mobility after surgery is mainly based on the measurement of the range of motion during imposed movements. It can thus be questionable if this assessment represents the mobility experienced during daily life. The goal of this study was to propose a new evaluation tool based on the monitoring of cervical spine movement during daily activities.

METHODS

The detection of cervical movement and the determination of primary motion component (lateral bending, axial rotation or flexion-extension), using two inertial sensors, were first validated in laboratory settings. Fifteen patients who underwent a cervical arthrodesis and nine healthy control subjects were monitored during their daily activity for half a day. The frequency of cervical movement was quantified according to posture, i.e. static and walking periods. The amplitude and velocity of cervical movement were evaluated using the median and cumulative distribution function.

FINDINGS

The movement detection and classification showed an excellent performance (sensitivity and specificity>94%). For the daily monitoring, the patients presented a movement frequency similar to controls, whereas the amplitude and velocity in patients were lower than in controls (P<0.05). The differences between patients and controls were larger for the velocity parameters (effect sizes>0.37 and >0.54 for static and walking periods respectively) than for the amplitude parameters.

INTERPRETATION

Body-worn inertial sensors enable the quantitative evaluation of global cervical movement. The movement amplitude and velocity during free-living conditions can be used as objective parameters to evaluate the cervical spine mobility after treatment.

Pelvic excision of large aggressive angiomyxoma in a woman: irradiation for recurrent disease

Aggressive angiomyxoma (AAM) is a rare tumor that preferentially involves the pelvis and perineal regions and arises from the connective tissue. Its cause and pathogenesis are unknown at present. Treatment typically involves surgery, and despite apparently complete resection, local recurrences are common. We describe a case of a large angiomyxoma of the left pelvis in a 59-year-old woman who underwent two surgical excisions. The first had been done in May 1998. She developed a local recurrence in December 1998. A palliative resection with macroscopic residuals was performed in February 2001, followed by radiation therapy with a total dose of 60 Gy. The diagnosis was revised at the time of the second operation. Initially, the tumor was diagnosed as angiomyofibroblastoma. Follow-up 3 years after the radiation treatment revealed no recurrence. The time of the local control achieved as yet is already longer than the former time to progression between the first two surgical procedures. This is, to our knowledge, the second description of a therapeutic irradiation of a recurrent AAM. Radiation therapy is able to control a recurrent AAM for at least 3 years.

Pelvic excision of large aggressive angiomyxoma in a woman: irradiation for recurrent disease

Aggressive angiomyxoma (AAM) is a rare tumor that preferentially involves the pelvis and perineal regions and arises from the connective tissue. Its cause and pathogenesis are unknown at present. Treatment typically involves surgery, and despite apparently complete resection, local recurrences are common. We describe a case of a large angiomyxoma of the left pelvis in a 59-year-old woman who underwent two surgical excisions. The first had been done in May 1998. She developed a local recurrence in December 1998. A palliative resection with macroscopic residuals was performed in February 2001, followed by radiation therapy with a total dose of 60 Gy. The diagnosis was revised at the time of the second operation. Initially, the tumor was diagnosed as angiomyofibroblastoma. Follow-up 3 years after the radiation treatment revealed no recurrence. The time of the local control achieved as yet is already longer than the former time to progression between the first two surgical procedures. This is, to our knowledge, the second description of a therapeutic irradiation of a recurrent AAM. Radiation therapy is able to control a recurrent AAM for at least 3 years.

Feto-maternal interface of human placenta inhibits angiogenesis in the chick chorioallantoic membrane (CAM) assay

The rapidly growing chorionic villi of the human placenta characteristically show constant blood vessel growth and differentiation. In contrast, the underlying decidua reveals tissue remodeling without apparent angiogenesis. Using the chick chorioallantoic membrane (CAM) assay, we found marked inhibition of angiogenesis by the feto-maternal interface tissue derived from nine human placentas obtained minutes after delivery. Inhibition was prevented by the addition of monensin, which blocks the release of synthesized cell products, and was markedly reduced by drying or freezing the tissue before the assay. Histology, combined with statistical analysis of the constituent cell types, correlated inhibition of angiogenesis with the number of fetally-derived extravillous trophoblasts in the feto-maternal interface tissue. Electron microscopy revealed endothelial cell damage in preexisting small (but not large) CAM vessels. We conclude that decidual tissue inhibited angiogenesis by releasing a water soluble factor which was under apparent constant production by vaible trophoblast on the CAM. The extravillous trophoblast population resembles tumor cells in its migratory and invasive properties but, in contrast to tumor induced angiogenesis, it is angiostatic, perhaps to counteract angiogenic proteins leaking from the intervillous space which could be detrimental to the maternal organism if active.

Increased excitatory amino acid levels in brain cysts of epileptic patients

We studied two epileptic patients with arachnoid brain cysts by proton magnetic resonance spectroscopy (1H MRS). In addition, histochemical analyses of surgical specimens, cerebrospinal fluid, and cystic fluid were performed in one of the patients. In both patients, greatly increased levels of excitatory amino acids (EAAs) glutamate and aspartate were present in the cystic fluid, while there was only a moderate increase of glutamate in the epileptogenic brain tissue adjacent to the cyst in one of the patients. In non epileptic brain regions, no elevations of the EAAs were present. Since EAAs are involved in induction and maintenance of epileptogenesis, their extremely high concentrations in the cystic fluid may explain seizures in some patients with such brain cysts. Our findings may have therapeutical consequences for patients with drug resistant epilepsy, in whom elevated concentrations of EAAs in the cysts can be verified. Surgery with the aim to create a communication between the cyst and the subarachnoidal space may prevent an accumulation of the EAAs and thus result in a relief of seizures.

[Spontaneous intracranial hypotension syndrome]

Spontaneous intracranial hypotension is a rare but well known entity first described by the German neurosurgeon Schaltenbrand. We report the clinical and radiological findings of four patients (2 males, 2 females, mean age 55 years) presenting with this clinical entity and peculiar constant MRI findings. Intense postural headache was present in all patients together with a very low CSF pressure at lumbar tap although none of the patients had any history of recent lumbar puncture, spinal or cerebral surgery or cranio-cervical trauma. MRI revealed in all patients an intense meningeal enhancement and thickening which was most prominent on the dural side of the subdural space. The ventricular system was thin, presenting almost like slit ventricules. A downward shift of the cerebellar tonsils and hemorrhagic subdural collections were also observed in two patients. Biopsy of meninges performed in two patients showed fibrosis of the leptomeninges together with signs of old hemorrhage in one case. We postulate that histologic and radiologic changes are due to chronic subdural bleeding in relation with abnormal displacement of the nervous structures due to intracranial hypotension. The underlying cause of spontaneous intracranial hypotension is rarely established and the course of the disease is benign. Some authors have advocated to perform isotopic cysternography in search for a CSF leak, particularly in the spine, that could be surgically corrected. No such investigation has been conducted yet in our patients because the spontaneous evolution has been mostly favorable.

Ultrastructural localization of SNAP-25 within the rat spinal cord and peripheral nervous system

Synaptosomal associated protein of 25 kDa (SNAP-25) has been implicated in the membrane fusion machinery of neurotransmitter release and axonal growth. Using immunocytochemistry, we have analyzed the distribution and ultrastructural localization of SNAP-25 in selected areas of the central and peripheral nervous systems of adult rats. We show that the protein is specifically expressed in the trans face of the Golgi apparatus and in the axonal compartment. In axons and nerve endings, SNAP-25 is localized to discrete areas of the membranes of most organelles such as the axoplasmic reticulum, the axolemma, the outer membrane of mitochondria and synaptic vesicles. This wide distribution of SNAP-25 suggests that the protein is involved in the fusion of membranes in the whole axonal compartment of neurons.

Cell-specific expression of epithelial sodium channel alpha, beta, and gamma subunits in aldosterone-responsive epithelia from the rat: localization by in situ hybridization and immunocytochemistry

A highly selective, amiloride-sensitive, epithelial sodium channel from rat colon (rENaC), composed of three homologous subunits termed alpha, beta, and gamma rENaC, has been cloned by functional expression and was proposed to mediate electrogenic sodium reabsorption in aldosterone-responsive epithelia. To determine whether rENaC could account for sodium absorption in vivo, we studied the cellular localization of the sodium channel messenger RNA subunits by in situ hybridization and their cellular and subcellular distribution by immunocytochemistry in the kidney, colon, salivary, and sweat glands of the rat. In the kidney, we show that the three subunit mRNAs are specifically co-expressed in the renal distal convoluted tubules (DCT), connecting tubules (CNT), cortical collecting ducts (CCD), and outer medullary collecting ducts (OMCD), but not in the inner medullary collecting ducts (IMCD). We demonstrate co-localization of alpha, beta, and gamma subunit proteins in the apical membrane of a majority of cells of CCD and OMCD. Our data indicate that alpha, beta, and gamma subunit mRNAs and proteins are co-expressed in the distal nephron (excepting IMCD), a localization that correlates with the previously described physiological expression of amiloride-sensitive electrogenic sodium transport. Our data, however, suggest that another sodium transport protein mediates electrogenic amiloride-sensitive sodium reabsorption in IMCD. We also localized rENaC to the surface epithelial cells of the distal colon and to the secretory ducts of the salivary gland and sweat gland, providing further evidence consistent with the hypothesis that the highly selective, amiloride-sensitive sodium channel is physiologically expressed in aldosterone-responsive cells.

Innervation of putative rapidly adapting mechanoreceptors by calbindin- and calretinin-immunoreactive primary sensory neurons in the rat

Calbindin and calretinin are two homologous calcium-binding proteins that are expressed by subpopulations of primary sensory neurons. In the present work, we have studied the distribution of the neurons expressing calbindin and calretinin in dorsal root ganglia of the rat and their peripheral projections. Calbindin and calretinin immunoreactivities were expressed by subpopulations of large- and small-sized primary sensory neurons and colocalized in a majority of large-sized ones. The axons emerging from calbindin- or calretinin-immunoreactive neurons innervated muscle spindles, Pacini corpuscles and subepidermal lamellar corpuscles in the glabrous skin, formed palisades of lanceolate endings around hairs and vibrissae, and gave rise to intraepidermal nerve endings in the digital skin. Since most of these afferents are considered as rapidly adapting mechanoreceptors, it is concluded that calbindin- or calretinin-expressing neurons innervate particular mechanoreceptors that display physiological characteristics of rapid adaptation to stimuli.

Peripheral projections of calretinin-immunoreactive primary sensory neurons in chick hindlimbs

In chicken dorsal root ganglia, calretinin immunoreactivity is expressed by a subpopulation of large A-neurons, most of which co-express calbindin D-28k. The myelinated axons of these neurons selectively innervate all muscle spindles and most Herbst corpuscles associated to feathers in hindlimbs. It is suggested that the presence of calretinin in primary afferents may be correlated with the electrophysiological properties of rapidly adapting mechanoreceptors.

Calbindin D-28k- and substance P-immunoreactive primary sensory neurons: peripheral projections in chick hindlimbs

The peripheral projections of two distinct subpopulations of primary sensory neurons, expressing either calbindin D-28k or substance P, were studied in chick hindlimbs by immunodetecting calbindin D-28k with a rabbit antiserum and substance P with a mouse monoclonal antibody. Calbindin D-28k-immunoreactive axons provided an innervation restricted to specific mechanoreceptors such as muscle spindles, Herbst and Merkel corpuscles, or collars of feather follicles but were absent from Golgi tendon organs. In contrast, substance P-positive axons spread out diffusely in muscles and skin, formed loose plexuses, and extended free branches to the endomysium, arteries, superficial dermis, or dermal pulp of feather follicles. The present results show that calbindin D-28k- and substance P-immunoreactive primary sensory neurons provide distinct modes of innervation to selective targets in peripheral tissues. The results suggest a possible correlation between CaBP-expressing nerve endings and rapidly adapting mechanoreceptors.

Changes in nuclear 3,5,3'-triiodothyronine receptor expression in rat dorsal root ganglia and sciatic nerve during development: comparison with regeneration

The action of the thyroid hormones on responsive cells in the peripheral nervous system requires the presence of nuclear triiodothyronine receptors (NT3R). These nuclear receptors, including both the alpha and beta subtypes of NT3R, were visualized by immunocytochemistry with the specific 2B3 monoclonal antibody. In the dorsal root ganglia (DRG) of rat embryos, NT3R immunoreactivity was first discretely revealed in a few neurons at embryonic day 14 (E14), then strongly expressed by all neurons at E17 and during the first postnatal week; all DRG neurons continued to possess clear NT3R immunostaining, which faded slightly with age. The peripheral glial cells in the DRG displayed a short-lived NT3R immunoreaction, starting at E17 and disappearing from the satellite and Schwann cells by postnatal days 3 and 7 respectively. In the developing sciatic nerve, Schwann cells also exhibited transient NT3R immunoreactivity restricted to a short period ranging from E17 to postnatal day 10; the NT3R immunostaining of the Schwann cells vanished proximodistally along the sciatic nerve, so that the Schwann cells rapidly became free of detectable NT3R immunostaining. However, after the transection or crushing of an adult sciatic nerve, the NT3R immunoreactivity reappeared in the Schwann cells adjacent to the lesion by 2 days, then along the distal segment in which the axons were degenerating, and finally disappeared by 45 days, when the regenerating axons were allowed to re-occupy the distal segment.(ABSTRACT TRUNCATED AT 250 WORDS)

The expression of nuclear 3,5,3' triiodothyronine receptors is induced in Schwann cells by nerve transection

The effects of thyroid hormones on the nervous system are mediated by the presence of nuclear T3 receptors (NT3R). In this study, the expression of NT3R was investigated in spinal cord, dorsal root ganglia (DRG), or sciatic nerve of adult rats after immunostaining with a 2B3-NT3R monoclonal antibody which recognizes both alpha and beta types of NT3R. The specificity of this monoclonal antibody was confirmed by Western blots. The 2B3-NT3R monoclonal antibody recognized one band corresponding to a molecular weight of 57 kDa in extract of spinal cord or DRG. No staining was observed on immunoblot of intact sciatic nerve. In the spinal cord, the nuclei of the neurons and glial cells including both astrocytes and oligodendrocytes exhibited 2B3-NT3R immunoreactivity. While all the nuclei of the DRG sensory neurons expressed the NT3R, all the nuclei of the satellite and Schwann cells were devoid of any immunoreaction. In the sciatic nerve, the nuclei of the Schwann cells also lacked 2B3-NT3R-immunoreactivity. After sciatic nerve transection in vivo, Schwann cell nuclei, which never expressed NT3R in intact nerves of adult rats, displayed a clear 2B3-NT3R immunoreaction in proximal and distal stumps adjacent to the section. Double immunostaining with antibodies raised to 3-sulfogalactosylceramide or S100 confirmed that most of the NT3R containing nuclei belong to Schwann cells. In dissociated cell cultures grown in vitro from sciatic nerves, Schwann cells exhibited 2B3-NT3R immunoreactivity. These data suggest that the inhibition of NT3R expression in Schwann cells ensheathing axons in intact nerve is reversed when the axons are degenerating or lacking.(ABSTRACT TRUNCATED AT 250 WORDS)

Substance P-like-immunoreactive sensory neurons in dorsal root ganglia of the chick embryo: ontogenesis and influence of peripheral targets

The expression of substance P (SP) was studied in sensory neurons of developing chick lumbosacral dorsal root ganglia (DRG) by using a mixture of periodic acid, lysine and paraformaldehyde as fixative and a monoclonal antibody for SP-like immunostaining. The first SP-like-immunoreactive DRG cells appeared first at E5, then rapidly increased in number to reach a peak (88% of ganglion cells) at E8, and finally declined (59% at E12, 51% after hatching). The fall of the SP-like-positive DRG cells resulted from two concomitant events affecting a subset of small B-neurons: a loss of neuronal SP-like immunoreactivity and cell death. After one hindlimb resection at an early (E6) or late (E12) stage of development (that is before or after establishment of peripheral connections), the DRG were examined 6 days later. In both cases, a drastic neuronal death occurred in the ispilateral DRG. However, the resection at E6 did not change the percentage of SP-like-positive neurons, while the resection at E12 severely reduced the proportion of SP-like-immunoreactive DRG cells (25%). In conclusion, connections established between DRG and peripheral target tissues not only promote the survival of sensory neurons, but also control the maintenance of SP-like-expression. Factors issued from innervated targets such as NGF would support the survival of SP-expressing DRG cells and enhance their SP content while other factors present in skeletal muscle or skin would hinder SP expression and therefore lower SP levels in a subset of primary sensory neurons.

Substance P and calbindin D-28k-immunoreactivity in primary sensory neurons of chick embryos: differential neuronal birthdates and transient co-localization

During the ontogenesis of dorsal root ganglia (DRG), the immunoreactivity to substance P (SP) and calbindin D-28k (CaBP) appears in chickens at embryonic day 5 (E5) and E10 respectively. To establish the birthdates of primary sensory neurons expressing SP or CaBP, chick embryos were given repetitive intra-amniotic injections of [3H]-thymidine. The neuroblasts giving rise to SP-expressing neurons were labeled up to E6 while those generating CaBP-immunoreactive neurons stopped to incorporate [3H]-thymidine before E5.5. This finding indicates that neurons exhibiting distinct phenotypes may originate from neuroblasts which arrest to proliferate at close but distinct stages of development. To determine whether SP and CaBP are co-expressed or not in DRG neurons, chick embryos at E12, E18, and chickens two weeks after hatching were perfused and fixed to detect simultaneously SP- and CaBP-immunoreactivity in DRG sections. The results showed that SP and CaBP were transiently co-expressed by a subset of neurons at E12. Later, however, the SP-immunoreactivity was gradually lost by these ganglion cells, so that the SP- and CaBP-immunoreaction defined two distinct neuronal subpopulations after hatching. In conclusion, most CaBP-immunoreactive DRG cells derive from a subset of neurons in which SP and CaBP are transiently co-localized.