Comparison of intraoperative frozen section analysis of sentinel node with preoperative positron emission tomography in the diagnosis of axillary lymph node status in breast cancer patients

BACKGROUND

Although axillary lymph node status is an important prognostic factor and axillary dissection is regarded as the gold standard for staging, it requires radical surgery which is accompanied by considerable postoperative problems such as lymphedema. This study was carried out to evaluate the diagnostic accuracy of preoperative positron emission tomography (PET) and intraoperative frozen biopsy of sentinel lymphadenectomy (SLND) in detecting axillary lymph node metastasis.

METHODS

We studied 18 patients who had preoperative PET and SLND for breast cancer in the Department of Surgery at Samsung Medical Center. They all had preoperative PET with a radiolabeled glucose analogue ([18F]FDG) to visualize primary tumors and metastatic nodes. Isosulphan blue dye was used for intraoperative SLND. Frozen and permanent biopsies were then compared after full axillary dissection.

RESULTS

In 18 cases, six had positive metastatic nodes in the permanent biopsy of full axillary dissection but were negative in three cases by preoperative PET. There was one false negative result by frozen biopsy of SLND which was later shown to be positive by permanent biopsy. The sensitivity and specificity of SLND and PET for detecting axillary node metastasis were 83, 100% and 50, 100%, respectively.

CONCLUSION

Although both methods are good for axillary nodal status, the intraoperative frozen biopsy result of SLND was superior to preoperative PET in our preliminary study.

The relationship between rabbit corneal opacity and immunohistochemical expression of heat shock protein 72/73 and c-fos after excimer laser photorefractive keratectomy

To evaluate the etiology of corneal opacities, a study was done on the immunohistochemical staining for heat shock protein (HSP) 72/73 and c-fos after myopic excimer laser photorefractive keratectomy (PRK). New Zealand white rabbits (60 eyes) were divided into four groups: -6-, -9- and -15-dpt operation groups and a control group (only corneal epithelium removed). Using an excimer laser (VisX 20/20, Sunnyvale, Calif., USA), myopic PRK was performed on the rabbit's cornea by a single or multizone technique followed by an immunohistochemical stain to detect the expression of HSP 72/73 and c-fos at 6, 24, 48 h, 1 week and 8 weeks. Corneal epithelia were healed within 3 days in all groups, and 8 weeks after the operation, the mean density of corneal opacity was 0.83 (-6-dpt operation group), 1 (-9-dpt operation group) and 1.67 (-15-dpt operation group). All groups exhibited HSP 73 in corneal epithelium and stroma. However, the maximal expression of c-fos and HSP 72 appeared in corneal epithelium at 24 and 48 h, respectively, after the operation in the -15-dpt group. These results suggest that the expressions of HSP 72 and c-fos in rabbit corneal epithelium are significant factors in relation to corneal opacity after excimer laser PRK.

Collagen-to-smooth muscle ratio helps prediction of prognosis after pyeloplasty

PURPOSE

We quantitatively evaluated the collagen-to-smooth muscle tissue matrix ratio in ureteropelvic junction obstruction, and compared the ratio with the degree of obstruction, patient age and postoperative renal recovery.

MATERIALS AND METHODS

We analyzed histological sections from 65 patients with ureteropelvic junction obstruction and 6 normal controls. Morphological and functional grading systems were adapted to determine the degree of renal obstruction. To examine smooth muscle and collagen tissue, sections were stained using Masson's trichrome. Two distinct populations of collagen versus smooth muscle were identified and the tissue matrix ratio was calculated by color image analysis.

RESULTS

The mean tissue matrix ratio plus or minus standard deviation was 1.32+/-0.79 in all patients with ureteropelvic junction obstruction but only 0.30+/-0.10 in normal controls (p <0.0001). It appeared that the lower the tissue matrix ratio, the better the improvement in postoperative hydronephrosis (r = -0.50, p = 0.0001). Better recovery of renal function after pyeloplasty was observed with a decrease in the tissue matrix ratio (r = -0.43, p = 0.0004). We divided patients according to the tissue matrix ratio into groups 1--ratio 1 or less, 2--greater than 1 to 1.5 and 3--greater than 1.5 to determine a more detailed and clinically applicable correlation of tissue matrix ratio with postoperative renal functional changes. Better improvement in postoperative renal function was observed in group 1 than in group 3 (p = 0.002). Also, the tissue matrix ratio increased with patient age (r = 0.33, p = 0.007).

CONCLUSIONS

Since our data represent an objective and quantitative parameter associated with ureteropelvic junction obstruction, we believe that our findings may help to predict the prognosis after pyeloplasty.

The role of nitric oxide and prostaglandin E2 on the hyperalgesia induced by excitatory amino acids in rats

The present study was designed to investigate the role of nitric oxide (NO), N-methyl-D-aspartate (NMDA) receptor and prostaglandins on hyperalgesia induced in rats by excitatory amino acids and the possibility that prostaglandins may act as the retrograde messenger in the spinal cord like NO. Nomega-nitro-L-arginine methyl ester (L-NAME; 500 microg/paw, intraplantarly (i.pl.)), MK-801 (10 microg/paw, i.pl.) or indomethacin (300 microg/paw, i.pl.) reduced the duration of phase 2 of the biting/licking and scratching (B/L + S) response induced by formalin injection from 255.6+/-16.7 s to 155.6+/-16.9, 172.25+/-33.3 or 205.6+/-16.7 s, respectively. L-NAME (0.3 mg, i.th.), MK-801 (8 microg, i.th.) or indomethacin (20 microg, i.th) reduced the duration of phase 2 of the B/L + S response induced by saline injection from 288.5+/-7.7s to 207.7+/-19.2, 184.6+/-7.7 or 1923+/-38.5 s, respectively. L-NAME or indomethacin injected into the spinal cord of the rat significantly reduced the hyperalgesia induced by NMDA (1 microg, i.th.) from 43.8+/-4.6% to 12.3+/-3.1 and 19.2+/-2.3%, respectively. It is assumed that NO produced by excitatory amino acids may increase prostaglandin production by cyclooxygenase activation. L-NAME, MK-801 or indomethacin injected into the rat spinal cord significantly reduced the hyperalgesia induced by prostaglandin E2 (PGE2, 25 ng, i.th.) in the tail-flick test from 40.6+/-3.5% to 18.2+/-3.2, 18.8+/-1.8 or 17.6+/-4.1%, respectively, but had little effect on hyperalgesia in the paw pressure test (except for indomethacin). In conclusion, NO and PGE2 affect the hyperalgesia induced by excitatory amino acids. It is suggested that PGE2, like NO, may act as a retrograde messenger in the spinal cord.

Synthesis of 4,6-dichloro-3-[(1-N-arylaminocarbonyl)-hydrazono]-1,3-dihydro-indole-2 -one as a potential NMDA receptor glycine site antagonist

A synthetic procedure for the preparation of indole-2,3-dione derivatives 6 as a potential NMDA receptor glycine site antagonist with improved pharmacological profile compared with 2-carboxyindole derivative 5, starting from readily available 3,5-dichloroaniline (7), is described.

Rapid, efficient detection and drug susceptibility testing of Mycobacterium tuberculosis in sputum by microscopic observation of broth cultures. The Tuberculosis Working Group in Peru

Inexpensive, rapid, and reliable methods of detecting infection by and drug susceptibility of Mycobacterium tuberculosis (MTB) are crucial to the control of tuberculosis. The novel microscopic observation broth-drug susceptibility assay (MODS) detects early growth of MTB in liquid medium, allowing more timely diagnosis and drug susceptibility testing. Sputum samples from hospitalized patients in Peru were analyzed by using stains, culture, and PCR. Sensitivity of MODS (92%) compared favorably with the most sensitive of the other culture methods (93%). Sputum samples positive for tuberculosis were tested for susceptibility to isoniazid and rifampin with the microwell alamar blue assay (MABA) and MODS. In 89% of cases, there was concordance between MODS and MABA. Of the diagnostic and susceptibility testing methods used, MODS yielded results most rapidly (median, 9.0 and 9.5 days, respectively). MODS is a rapid, inexpensive, sensitive, and specific method for MTB detection and susceptibility testing; it is particularly appropriate for use in developing countries burdened by significant infection rates and increasing numbers of multiple-drug-resistant cases.

Morphologic change of the internal elastic lamina in Buerger's disease

Morphologic features and pathogenesis of arterial changes occurring in Buerger's disease (thromboangiitis obliterans) are still controversial. This study describes histopathologic features of medium sized arteries from patients with Buerger's disease, particularly of the internal elastic lamina in relation to the immunologic mechanism of the injury. Seventeen segments of occluded arteries (femoral or popliteal arteries) from 17 patients with Buerger's disease were analyzed by histopathological and immunohistochemical methods. The most characteristic features were total luminal obliteration, together with a varying degree of recanalization and deposition of hemosiderin pigments. Detailed analysis, however, showed marked undulation and multiplication of the internal elastic lamina (100%) associated with basophilic degeneration and delicate linear calcification (47%). Lymphocytic infiltration along the internal elastic lamina was seen in 71% and was associated with localized edema. Lymphocytes along the lamina were consistently positive for T cell marker. Mild to moderate fibrosis was present at the media in 24%. Adventitial changes included mild, nonspecific and irregular fibrosis seen in 53%. Immunologic injury to the internal elastic lamina associated with T-lymphocytic infiltration might be the initial morphogenetic mechanism of the thrombotic occlusion and organization of medium-sized arteries in Buerger's disease.

p53 codon 72 polymorphism and risk of cervical carcinoma in Korean women

A common polymorphism of the wild type p53 is known at codon 72 of exon 4, with 2 alleles encoding either arginine (CGC, p53Arg) or proline (CCC, p53Pro). A recent study suggested that this polymorphism affects the susceptibility of p53 protein to human papillomavirus E6 oncoprotein mediated degradation and that individuals homozygous for p53Arg are seven times more susceptible to HPV-associated carcinogenesis of the cervix than heterozygotes. To examine whether the p53Arg genotype could be a risk factor for HPV-associated cervical carcinomas in the Korean population, we analyzed the p53 codon 72 polymorphism status of HPV-positive invasive cervical carcinomas from 52 Korean women and 103 healthy control samples. The proportion of individuals homozygous for p53Arg, homozygous for p53Pro, and heterozygous for the two alleles were 40%, 19%, and 41% in normal healthy controls; 42%, 17%, and 40% in women with HPV-positive invasive cervical carcinoma. There were no significant differences in the distribution of p53 genotypes between controls and cervical carcinomas. This finding indicates that the p53Arg genotype is not associated with an increased susceptibility to cervical carcinoma in Korean women.

Ultrastructural changes in microvessel with age in the hippocampus of senescence-accelerated mouse (SAM)-P/10

Microvessels in the hippocampus of aged SAM-P/10 (14 months old) showed the following ultrastructural changes compared with those of young-mature controls (3 months old): (1) the majority of capillaries had lost the smooth contours typical of young cases; (2) the luminal surface of capillaries showed irregularity; (3) the endothelial cytoplasm was thicker; (4) vesicles appeared more frequently in the endothelium; (5) interendothelial tight junctions and basement membranes, however, seemed to show no significant abnormalities; (6) pericytes, especially those of arterioles and venules, contained many enlarged cytoplasmic inclusions with honeycomb-like vacuoles; (7) the area of glial perivascular end feet was greater. These morphological findings raise the possibility of impaired blood-brain barrier function and microhemodynamic disturbances in aged SAM-P/10 hippocampus.

Stereoisomeric acylamidomorpholinium carnitine analogues: selective inhibitors of carnitine palmitoyltransferase I and II

Acylamidomorpholinium carnitine analogues, 6-(tetradecanamidomethyl- and -hexadecanamidomethyl)-4,4-dimethylmorpholin-4-ium-2-a cetate, 1, synthesized as complete sets of stereoisomers, were assayed as inhibitors for isozymes of carnitine palmitoyltransferase (CPT). Microsomal CPT isoymes showed modest discrimination among the stereoisomers; while rat-liver mitochondrial CPT-I and CPT-II showed distinct differences. The tetradecanamidomethyl analogue of (2R,6S)-1 activated CPT-I but inhibited CPT-II.

Anesthetic management for cesarean section in a pregnant woman with impending acute liver failure--a case report

Acute liver failure includes a constellation of clinical conditions resulting from rapid loss of hepatocyte function. The anesthesiologist may often be asked to anesthetize a patient with acute liver failure before the etiological entity of disease can be completely clarified. Most of the previous reports were concentrated in obstetric or hepatological periodicals. Reports about anesthesia for such patients are scanty. We present a case about a near term pregnant woman with a complication diagnosed as impending acute liver failure, who received total intravenous anesthesia for emergent cesarean section. Pros and cons of different anesthetic techniques for this condition are discussed.

A new study of bacterial motion: superconducting quantum interference device microscopy of magnetotactic bacteria

The recently developed "microscope" based on a high-Tc dc SQUID (superconducting quantum interference device) is used to detect the magnetic fields produced by the motion of magnetotactic bacteria, which have permanent dipole moments. The bacteria, in growth medium at room temperature, can be brought to within 15 micron of a SQUID at liquid nitrogen temperature. Measurements are performed on both motile and nonmotile bacteria. In the nonmotile case, we obtain the power spectrum of the magnetic field noise produced by the rotational Brownian motion of the ensemble of bacteria. Furthermore, we measure the time-dependent field produced by the ensemble in response to an applied uniform magnetic field. In the motile case, we obtain the magnetic field power spectra produced by the swimming bacteria. Combined, these measurements determine the average rotational drag coefficient, magnetic moment, and the frequency and amplitude of the vibrational and rotational modes of the bacteria in a unified set of measurements. In addition, the microscope can easily resolve the motion of a single bacterium. This technique can be extended to any cell to which a magnetic tag can be attached.

Erythrophagocytosis and iron deposition in atherosclerotic lesions

Iron deposition has been shown to be prominent in atherosclerotic lesions. However, the source of iron accumulated in arterial walls is unclear. In present report, we provide the histological evidence to demonstrate the localization of erythrocytes in atherosclerotic lesions from experimental animals. As revealed by scanning and transmission electron microscopy, the circulating erythrocytes were found to be present in intima of atherosclerotic aortas from apoE-deficient mice. These erythrocytes appeared to be readily phagocytosed by macrophages in lesions. The erythrophagocytosis was also evident in lesions from cholesterol-fed rabbits. Furthermore, the iron deposition was detectable in the region with erythrocytes. When the aortic sections of humans and apoE-deficient mice were immunostained with specific antibody to hemoglobin, it was clearly shown that the positive stain was detectable in macrophage-derived foam cells. Immunostaining of serial sections with specific antibodies to heme oxygenase-1 (HO-1) and ferritin further demonstrated the colocalization of HO-1 and ferritin in area with positive immunoreactivity for hemoglobin. Likewise, Perls' reaction revealed the positive iron stain in the same region. Collectively, these results suggest that hemoglobin/heme released from the phagocytosed erythrocytes may contribute to at least part of iron deposited in atherosclerotic lesions.

Iron-deficient diet reduces atherosclerotic lesions in apoE-deficient mice

BACKGROUND

Iron deposition is evident in human atherosclerotic lesions, suggesting that iron may play a role in the development of atherosclerosis. To test this idea, the correlation between the extent of iron deposition and the severity of atherosclerosis in apolipoprotein E (apoE)-deficient mice was investigated. Furthermore, the effect of a low-iron diet on the progression of atherosclerotic lesions in these animals was evaluated.

METHODS AND RESULTS

Iron deposition in tissues of apoE-deficient mice was examined by Perls' staining method. The results clearly demonstrated that iron deposits are present in atherosclerotic lesions and tissue sections of heart and liver in an age-dependent manner. When the young mice received a low-iron diet for 3 months, the hematocrit, serum iron, hemoglobin, and cholesterol concentrations were not significantly altered compared with those of littermates placed on a chow diet. However, the serum ferritin level of animals in the iron-restricted group was 27% to 30% lower than that of the control group in either sex. Furthermore, the lipoproteins isolated from the iron-restricted group exhibited greater resistance to copper-induced oxidation. Histological examination revealed that atherosclerotic lesions developed in mice fed a low-iron diet were significantly smaller than those found in control littermates. Likewise, the iron deposition as well as tissue iron content was much less in aortic tissues of the iron-restricted animals. Circulating autoantibodies to oxidized LDL and immunostains for epitopes of malondialdehyde-modified LDL detected on lesions were also significantly lower in mice fed a low-iron diet.

CONCLUSIONS

Iron deposition is closely associated with the progression of atherosclerosis in apoE-deficient mice. Restriction in dietary iron intake leads to significant inhibition of lesion formation in these animals. These results suggest that the beneficial effect of a low-iron diet may be mediated, at least in part, by the reduction of iron deposition as well as LDL oxidation in vascular lesions.

HELLP syndrome with antepartum pulmonary edema--a case report

A 44-year-old pregnant female with a gestation of 29 weeks suddenly developed abdominal pain, nausea, vomiting, and laboratory study showed anemia, elevated liver enzymes, and lower platelets. HELLP syndrome was diagnosed and urgent delivery was needed. In order to correct the plasma volume and platelet deficiency, 6 units of both fresh frozen plasma and platelets, were given before operation. However, acute pulmonary edema was noted in the antepartum period. After vigorous treatment, she gave birth to a male infant. The postoperative course was smooth and she and her baby were discharged eleven days later. This case reminded us once again of the importance and necessity of invasive monitoring in fluid management of these patients.

The role of interleukin 12 in the development of atherosclerosis in ApoE-deficient mice

The cytokine profile of atherosclerotic aortas from apoE-deficient mice was assessed by reverse transcriptase-polymerase chain reaction. The results clearly showed that the expression of mRNA for IL-12p40 was evident in aortas from 3-month-old apoE-deficient mice. The mRNA for IL-10 was detected in aorta from these mice at the age of 6 months, indicating that expression of IL-12 is earlier than that of IL-10 in these animals. Concurrent with IL-12p40, the mRNA for the T-cell cytokine IFN-gamma, but not IL-4, was detected in aortas of mice at young and old ages. Both in situ hybridization and immunostaining further demonstrated the localization of IL-12 in macrophages of atherosclerotic lesions. Immunohistochemistry also demonstrated the expression of costimulatory molecules B7-1 and B7-2 in macrophages, suggesting that activation of T lymphocytes by macrophages may occur via surface antigens in lesions. When the immunoglobulin isotype of the antioxidized LDL antibodies in sera of apoE-deficient mice was determined, it revealed that both IgM and IgG were present. Furthermore, IgG2a is predominant and comprises approximately 50% of the antioxidized LDL IgG in sera from young mice (3 months), but decreased to lower levels (35%) in older mice (6 months). Daily administration of IL-12 led to an increase in serum levels of antioxidized LDL antibodies and accelerated atherosclerosis in young apoE-deficient mice compared with control mice injected with PBS alone. Taken together, these data suggest that IL-12 plays an active role in regulating the immune response during the early phase of atherosclerosis in apoE-deficient mice.

Frequent loss of imprinting of the H19 and IGF-II genes in ovarian tumors

Several human imprinted genes have been identified and are implicated in genetic diseases and tumorigenesis. We studied alterations of two imprinted genes, the paternally imprinted H19 and maternally imprinted IGF2, in 15 ovarian tumors with various cell types. To know allele-specific expression of the two genes, we analyzed restriction fragment length polymorphisms (RFLPs) at the 3'-untranslated region (UTR) in their cDNA, compared with those in the respective genomic DNA. As a result, biallelic H19 and IGF2 expression was observed in 8 (62%) of 13 informative (heterozygous) ovarian cancers and in 6 of 11 informative cases, respectively. H19 loss of imprinting (LOI) was most frequently observed in malignant serous cystadenocarcinoma (in four of six cases), whereas IGF2 LOI was not common in malignant epithelial cancers because three of six such LOI events occurred in benign mucinous cystadenomas and non-cancerous endometriotic cyst. Our data suggest that the alteration of H19 and IGF2 imprinting plays differential roles in tumorigenesis and progression of ovarian tumors, depending on the tissue type as well as the developmental stage. Our data may argue against tumor suppressor activity of H19 in ovarian cancers.

The epidermoid formation and its affinity to congenital cholesteatoma

The epidermoid formation was reinvestigated in stained step sections of foetal and neonatal temporal bones to assess its relationship to congenital cholesteatoma. Epidermoid formations were found in 88 of 211 temporal bones (42%) at from 12 weeks gestation to 6 months post-partum. The site was usually near the roof of the anterolateral epitympanum at an average of 389 microns anterior to the anterior edge of the tympanic membrane. Seven epidermoid formations however, were sited on the medial anterosuperior tympanic membrane surface. The mean surface diameter of epidermoid formations was 242 microns. Some were greater than 1500 microns, which approaches the size of small congenital cholesteatomas. They are often in proximity to a developmental epithelial fold which could close off to produce a cyst. These features support the concept that the epidermoid formation is a precursor of the small anterosuperior congenital cholesteatoma.

Multiple lymphomatous polyposis of the gut: case report

Multiple lymphomatous polyposis (MLP) is an uncommon type of primary non-Hodgkin's gastrointestinal B-cell lymphoma characterized by the presence of multiple lymphomatous polyps along the gut. We present a patient with MLP in which the involvement was unusually widespread. The diagnosis was confirmed by the typical polyposis lesion, histology, phenotyping and clinical presentations. A 68-year-old man had a large mass at the ileocecal valve as well as multiple polyps along the whole digestive tract. At the time of diagnosis, lymphoma had involved bone marrow, peripheral blood, spleen, prostate and peripheral lymph nodes. The patient received 8 courses of chemotherapy with no remission. He died of pneumonia 11 months after diagnosis. Clinically, the diagnosis may be confused with epithelial polyps; and histologically, the diagnosis must be distinguished from benign lymphoid proliferations as well as other types of lymphoma. The prognosis for patients with MLP is relatively poor (the median survival is usually less than 3 years).

The role of the primary visual cortex in higher level vision

In the classical feed-forward, modular view of visual processing, the primary visual cortex (area V1) is a module that serves to extract local features such as edges and bars. Representation and recognition of objects are thought to be functions of higher extrastriate cortical areas. This paper presents neurophysiological data that show the later part of V1 neurons' responses reflecting higher order perceptual computations related to Ullman's (Cognition 1984; 18:97-159) visual routines and Marr's (Vision NJ: Freeman 1982) full primal sketch, 2 1/2D sketch and 3D model. Based on theoretical reasoning and the experimental evidence, we propose a possible reinterpretation of the functional role of V1. In this framework, because of V1 neurons' precise encoding of orientation and spatial information, higher level perceptual computations and representations that involve high resolution details, fine geometry and spatial precision would necessarily involve V1 and be reflected in the later part of its neurons' activities.

Colocalization of iron and ceroid in human atherosclerotic lesions

The presence of ceroid, a complex of protein associated with oxidized lipids, is commonly observed in human atherosclerotic lesions. When the human aortic walls were examined by Perls' staining, it was found that the iron deposits were evident in aortas with atherosclerosis. The extent of iron deposition was associated with the severity of the lesion. Furthermore, the iron deposits appeared to be colocalized with ceroids either extracellularly or intracellularly in foam cell-like macrophages or smooth muscle cells. Electron microscopy and X-ray microanalysis revealed that some of the extracellular iron aggregates were present within the ceroids. Likewise, some of the subcellular iron aggregates were found to be located near the lipid droplets or within the ceroids of foam cells. Collectively, these observations support the theory that the lipid oxidation occurring in lipid-laden cells of aortic lesions is facilitated by iron-overload in these cells.

Expression of heme oxygenase-1 in atherosclerotic lesions

Heme oxygenase-1 (HO-1) is a heme-degradation enzyme induced under various oxidative stress conditions. To elucidate the potential involvement of HO-1 in atherogenesis, the expression of this enzyme in atherosclerotic lesions of apolipoprotein E-deficient mice and humans were examined. Both immunostaining and in situ hybridization clearly demonstrated that the expression of HO-1 was prominent in endothelium and foam cells/macrophages of thickened intima in lesions from both humans and experimental animals. The expression of this enzyme was also detected in medial smooth muscle cells of advanced lesions. The induction of HO-1 mRNA was observed in murine peritoneal macrophages after treatment with oxidized low density lipoprotein (LDL) but not with native LDL in a dose-dependent manner. Time course study demonstrated that the induction was prominent at 3 hours, reached a maximal induction at 6 hours, and remained evident up to 24 hours after oxidized LDL treatment. The degree of induction was in concordant with the extent of oxidation in the LDL preparation. Lysophosphatidylcholine, one of the major components present in oxidized LDL, was ineffective to induce the gene expression, suggesting that other lipophilic substances derived from LDL oxidation are responsible for the induction of HO-1. These results clearly demonstrate that HO-1 is one of the stress proteins expressed in atherosclerotic lesions.

Postnatal development of somatostatin- and neuropeptide Y-immunoreactive neurons in rat cerebral cortex: a double-labeling immunohistochemical study

The postnatal development of somatostatin (SOM)- and neuropeptide Y (NPY)-immunoreactive (ir) neurons was examined in rat cerebral cortex, while considering their coexistence in cortical neurons. Using double immunohistochemical staining for SOM and NPY with diaminobenzidine and benzidine dihydrochloride as chromogens, we subdivided immunoreactive cells into double-labeled SOM/NPY-, SOM only-, and NPY only-ir neurons. SOM/NPY- and SOM only-ir neurons were detectable even at the day of birth, in contrast on NPY only-ir cells which first appeared in most cortices from week two. The morphological features of double-labeled SOM/NPY neurons differed with those of SOM only- and NPY only-ir neurons. No apparent changes in the shape and size of single-labeled neurons occurred with age; throughout their postnatal life they were round and ovoid, had a thin rim of perinuclear cytoplasm, and short processes. However, the features of SOM/NPY-ir neurons were not consistent according to postnatal age; by day P7, these neurons showed immature features and they began to show more advanced neuronal characteristics by week P2, when they had a larger and more intensely-stain cytoplasm. In addition, their processes were longer, thicker and more complex than at earlier ages. At this age, SOM/NPY-ir somata were close to their near maximum size. From week P4, they became smaller and were lightly labeled. SOM/NPY-ir somata were larger than SOM only- and NYP only-ir somata at and after two weeks of age. The present results, showing different postnatal maturation patterns such as time of appearance and morphological features, raise the possibilities that double-labeled SOM/NPY and single-labeled immunoreactive neurons may be different populations regulated by different mechanisms in their development, and with different functional properties during development.