Baldev B. Singh

Filiform Papillae of Cat Tongue

A pronounced species variation in the organization of filiform papillae has been observed. Preliminary histologic studies of cat tongue revealed marked regional variations in size, shape and organization of filiform papillae. Therefore, a correlated light microscopic, transmission and scanning electron microscopic study of tissue samples of representative areas of the cat tongue was undertaken for further elucidation. Results showed that filiform papillae on the tip of the tongue were short and exhibited several conical processes from the base of each papilla. In contrast, filiform papillae in the midportion of the dorsum of the tongue consisted of a large mound with a single sharp spinous process projecting posteriorly. In the region of the vallate papillae, the filiform papillae were shorter and more conical than those on the midportion of the tongue. In addition, keratohyalin granules in filiform papillae were comprised of an eosinophil spheroid with small basophil attachments.

Immunohistochemical evaluation of bcl-2 oncoprotein in oral dysplasia and carcinoma

The proto-oncogene bcl-2 is associated with follicular lymphoma involving translocation t(14;18)(q32;q21) and is also overexpressed in various neoplasms. We report deregulation of bcl-2 expression during progression from oral epithelial dysplasia to squamous cell carcinoma. Immunohistochemical analysis with monoclonal antibodies to bcl-2 oncoprotein in formalin-fixed paraffin-embedded tissue sections revealed that severe epithelial dysplasias had a higher percentage of immunoreactivity than did mild and moderate dysplasias and squamous cell carcinomas. Expression of this oncoprotein was directly proportional to the degree of epithelial dysplasia, and nondysplastic basal cells contiguous to neoplastic lesions also expressed bcl-2. These findings, along with down-regulation of bcl-2 in differentiating carcinomas, suggest a role for this oncoprotein in relatively early stages of oral tumor progression. Differentiating neoplastic cells with marginal or no bcl-2 reactivity showed heterogeneous cell labeling of varying intensity for differentiation-associated cytokeratin (CK13), indicating their inverse topographic relationship.

Basement membrane changes under neoplastic oral mucous membrane. Ultrastructural observations, review of the literature, and a unifying concept.

This study explores the morphologic nature of the basement membrane under neoplastic oral mucous membrane. Of particular interest is the progression of changes associated with dysplasia, carcinoma in situ, and invasive carcinoma. On the basis of a critical review of the literature and our own ultrastructural observations, we present a unifying concept for the development of these basement membrane changes. This concept proposes that neoplastic epithelial cells may produce a collagenolytic enzyme which is released into the epithelial intercellular spaces. This enzyme permeates to the basement membrane, causes breaks in the basement membrane, and focal loss of stromal area contiguous with intercellular spaces. The neoplastic basal cells develop pseudopodia that eventually extend through the breaks in the basement membrane. This concept suggests that the basement membrane changes herald the progression of carcinoma in situ to invasive carcinoma.

Quantitative concentration profiling of nickel in tissues around metal implants: a new biomedical application of laser ablation sector field ICP-MS

Laser-ablation sector-field (high resolution) inductively coupled plasma mass spectrometry (LA-HR-ICP-MS) has been used for in situ determination and spatial elemental profiling of nickel concentrations in tissues that have been exposed to nickel wire. Nickel has a number of adverse biological effects that have made the use of nickel (or any other metal) in biomedical implants controversial. Yet, information about the distribution of nickel in tissues around nickel-containing implants is scarce. This study examines the diffusion of nickel with time and the spatial distribution of nickel around nickel-containing implants in vivo. Pure nickel wires were implanted subcutaneously into rats for seven days and the tissues were analyzed for nickel content and degree of inflammation away from the implants using 24Mg and 60Ni isotopes. Data were obtained by ablation with Nd:YAG laser operating in the UV region (266 nm and 213 nm) and element analysis with a high resolution ICP-MS. A 50 ppm glass standard (NIST-612) was also analyzed for the same isotopes. Quantification was performed by assuming a uniform nominal magnesium concentration value of 97 µg g−1 in untreated tissue and using 24Mg intensity for internal calibration. The precision (RSD%) of measurements for 24Mg for the NIST-612 Glass standard was within 3.8% to 4.6% and for the tissue samples was within 3.2% to 4.5%. The precision of analysis for 60Ni for the NIST-612 Glass standard was 5.4%. There was a significant penetration of nickel ions into tissues exposed to nickel wire implants. The concentration of nickel reached values as high as 60 µg g−1 near the implants, falling exponentially to undetectable levels 3–4 mm from the implants. The study showed that the laser ablation technique was well suited for analysis of soft tissues for metal ion content. This technique also allowed metal concentration spatial profiling as a function of time.

Studies on oral submucous fibrosis: III. Epithelial changes

The literature on the epithelial changes in oral submucous fibrosis is reviewed. The epithelial changes seen in thirty-eight biopsy specimens from thirty-eight patients with oral submucous fibrosis are presented in detail. It was seen that in submucous fibrosis there is a tendency toward epithelial atrophy associated with hyperothokeratosis and pyknotic changes in the nuclei of the basal-cell layer. Hyperplasia of the epithelium usually associated with hyperparakeratosis was also noticed. A striking feature in this study was the absence of glycogen from most of the Grade III (severe) cases. Vacuolization of prickle-cell layer, increased mitotic activity, and epithelial atypia were also noticed in a few cases. The significance of submucous fibrosis as a possible precancerous lesion is emphasized, with reference to the recent reports in the literature.

Effectiveness of a medicament containing silicon dioxide, aloe, and allantoin on aphthous stomatitis

This research protocol was designed to test the effectiveness of a gel containing silicon dioxide, aloe vera, and allantoin in the healing of recurrent aphthous ulcers. The subjects were patients with histories of developing multiple ulcers on the oral mucosa during a 3-to-4-month period. The parameters used to evaluate healing were number of lesions during a 3-to-4-month period, length of the interval between ulcers, size of ulcers, and pain from ulcers. An approach was used in which data were accumulated from diaries maintained by the subjects throughout the study intervals. Because 3 active substances were present in the gel, a preliminary study (study I) was performed to indicate the effect of each active substance and each combination. In this phase, different combinations of the substances were compared with the use of the 2(3) factorial experimental design. The results of this study demonstrated that statistical differences in the durations of lesions (P = .017) were present when all 3 substances were included in the gel. In the next study (study II), which was initiated to test the results of study I, additional subjects were divided into 2 groups; one used a control gel with silicon dioxide, and the other a gel with all 3 active substances. Study II found no statistical differences in the parameters when the 2 groups were compared. In study III, a modified crossover design was used with the subjects of study II, and a significant difference was found in lesion-free intervals (P = .0335) and length of time for the study (P = .0001). The differences in lesion intervals may have been caused by the differences in study length. Alteration in the occurrence of aphthous ulcers was demonstrated by the reduction in numbers of lesions in study I and by the increase in length of intervals between lesions in study III. However, a consistent pattern was not present; this indicated a lack of effect of the gel on aphthous ulcers.

A Mechanism-Based In Vitro Anticancer Drug Screening Approach for Phenolic Phytochemicals

Plant-derived phenolic compounds, including polyphenols (e.g., tannins), flavonoids, and phenolic acids, have been under investigation for their anticancer therapeutic and chemoprevention properties. Recently, certain mechanisms underlying the differential effects of green tea polyphenols (GTPPs) on tumor versus normal cells have been determined. These suggest that GTPPs may simultaneously activate multiple pathways. However, existing screening methods are insufficient for the identification of agents that possess both a cytotoxic effect on tumor cells and a protective effect on normal cells. The current study describes the establishment of an in vitro survival/apoptosis testing system based on detecting these mechanisms by a double-fluorescence method. This system is able to screen potential chemopreventive or therapeutic agents from (but not limited to) plant-derived compounds based on the pathways differentially activated by the agents. Tumor cell death and normal cell survival are detected simultaneously, in a device that co-cultures normal human cells adjacent to human tumor cells.

Transforming growth factor β1 dysregulation in a human oral carcinoma tumour progression model

Abstract. A human oral tumour progression model was established that consists of normal epithelial cells and three cell lines representing stages from dysplastic to metastatic cells. To investigate the impact of exogenous transforming growth factor‐β1 on this model system, we analysed the responsiveness of those cells to transforming growth factor‐β1 and explored the potential mechanism underlying the transforming growth factor‐β1 activity. We found that the growth of all cell types, regardless of their stage of tumour progression, is inhibited by transforming growth factor‐β1, although to different degrees. Transforming growth factor‐β1 induced the expression of cyclin‐dependent kinase inhibitors p15INK4B, p21WAF1/CIP1 and p27KIP1. In contrast, transforming growth factor‐β1 was found to stimulate the invasive potential of one cell type that represents the most advanced stage of tumour phenotype, suggesting that the impact of transforming growth factor‐β1 on functional features of tumour cells other than cellular proliferation may play a significant role in the process of oral tumour progression.

Ultrastructural and autoradiographic observations of hamster cheek pouch epithelium grown in vitro.

SummaryEpithelial outgrowths from hamster cheek pouch explants were cultured for varying peroids of time up to 22 days. Growth of the epithelial sheets was monitored, employing colcemid for demonstrating mitotic activity and tritiated thymidine for DNA synthesis. Mitoses and thymidine uptake were observed among epithelial outgrowths at a considerable distance from the original explant. The epithelial nature of the growing cell sheets was confirmed, employing electron microscopic techniques. The cells exhibited the presence of tonofilaments, desmosomes, ribosomes, Golgi, mitochondria, and rough endoplasmic reticulum. The cultured explants were treated with cyclic nucleotides in order to investigate their modulatory effects on epithelial cell differentiation. Dibutyryl cAMP induced marked mitotic inhibition (46.3%) in our assay, which was increased to 57% with the addition of theophylline. Dibutyryl cGMP showed only a mild (5%) stimulatory effect on mitotic activity. Dibutyryl cAMP enhanced keratinization in the epithelial cell out-growths with the biogenesis of keratohyalin granules, whereas dibutyryl cGMP did not produce any observable alterations.

Sex hormone receptor status of the dental pulp and lesions of pulpal origin.

OBJECTIVE The purpose of this study was to determine whether the dental pulp and lesions of pulpal origin (eg, pulp polyps, periapical granulomas, and periapical cysts) exhibit receptors for the sex steroid hormones estrogen, progesterone, and androgen. STUDY DESIGN Staining for the receptors of the hormones estrogen, progesterone, and androgen was accomplished through use of available immunohistochemical detection techniques. Pulpal tissues were obtained from freshly extracted human third molars; the other tissues were obtained from the Oral and Maxillofacial Pathology Laboratory archives. Ten samples of each tissue were processed and immunostained for these specific receptors. RESULTS Staining for estrogen and androgen receptors was essentially negative for all cell populations examined. However, positive progesterone receptor staining of varying degrees was noted in 8 of 10 pulpal specimens. Primarily, pulpal fibroblasts and odontoblasts exhibited positive immunoreactivity. CONCLUSIONS The results of this study suggest that although the dental pulp may be a potential target tissue for progesterone, evidence is lacking with respect to the other sex steroid hormones.