Expression of matrix metalloproteinase-9 (gelatinase B) in benign, premalignant and malignant laryngeal lesions

The matrix metalloproteinases (MMPs) are a family of proteolytic zinc-containing enzymes, which are responsible for the breakdown of the extracellular matrix components in pathological and physiological conditions. They are involved in basement membrane disruption, stroma and blood vessel penetration, metastasis and more recently there is evidence that they participate in tumor growth and angiogenic events. Matrix metalloproteinase 2 and 9 (MMP 2 and 9) belong to the gelatinases, a subgroup of MMPs, and have the capacity to degrade the triple helix type IV collagen of basal lamina of the basement membrane. With the present study, we tried to demonstrate the expression of MMP-9 immunohistochemically, comparatively in benign, premalignant and malignant lesions of the larynx. We studied 154 laryngeal lesions including 55 squamous cell carcinomas, 8 in situ carcinomas, 54 cases of dysplasia (of low and intermediate grade), 13 papillomas and 24 cases of keratosis. Overexpression of MMP 9 was observed in 74.4% and 50% in invasive and in situ squamous cell carcinomas respectively. In dysplastic cases, in papillomas and in keratoses the percentage of overexpression was 62.9%, 61.53% and 54.16% respectively and the expression of MMP-9 was significantly higher in invasive squamous cell carcinomas compared to dysplasias (p=0.000004). Also significantly higher was the expression of MMP-9 in dysplastic cases compared to papillomas (p=0.023). The MMP-9 expression was related neither to survival nor to the other available clinicopathological parameters (tumor size, grade, clinical stage, lymph node status and patient age). In conclusion, our study indicates that the expression of MMP-9 is up-regulated in a stepwise fashion, with two main steps, the first one, when a dysplastic lesion evolves and the next one, when the dysplasia progresses to invasive carcinoma.

Laryngeal involvement in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting the synovial membrane, which causes joint damage and bone destruction. Extra-articular manifestations are numerous, involving multiple organ systems. Rheumatoid nodules are common extra-articular findings occurring in 20% RA patients. They develop most commonly in pressure areas (elbows and finger joints) and may occasionally affect internal organs including pleura, lungs, meninges, larynx, and others. Furthermore, RA affects the ear, nose, and throat, causing various otorhinolaryngological symptoms. In this report we describe two patients with RA and laryngeal involvement, mostly rheumatoid nodule formation, with a review of the literature.

Effects of cigarette smoking on the antioxidant defence in young healthy male volunteers

Cigarette smoking induces a significant oxidant effect related to variety of free radical-related diseases often affecting the upper respiratory tract, unless it is effectively compensated by the antioxidant barriers of the humans. In the present study, the evaluation of the antioxidant compensatory mechanisms, by estimating the antioxidant capacity of extracellular defence (saliva and plasma) and the intracellular resistance of peripheral lymphocytes to oxidative stress in young healthy smokers, was investigated. Twenty young healthy male smokers and 20 age-matched non-smokers with similar dietary profiles were enrolled in the study. Total saliva and plasma samples were collected from both groups, and total antioxidant capacity (TAC) and lag time were estimated. The latter was also repeated in smokers just after a cigarette smoking. Peripheral lymphocytes isolated from the subjects of both groups were also tested for their inherent DNA damage as well as for their ability to resist H2O2-induced DNA damage by using the comet assay. TAC of plasma was found significantly higher in smokers compared to non-smokers (p <0.004), whereas no difference was recorded in plasma lag time values. Lymphocytes of smokers manifested a significantly decreased oxidant resistance (increased DNA fragmentation) to H2O2, in comparison to non-smokers. Our results indicate that young smokers do not manifest different salivary antioxidant defence than non-smokers. They exhibit, however, a higher plasma antioxidant capacity, but a significantly reduced ability of blood lymphocytes, to resist to H2O2-induced DNA damage.

A clinical case report of a Schwannoma on the tip of the tongue

OBJECTIVES

Schwannomas (neurilemmomas) are benign solitary tumours which arise from the Schwann cells of the neural sheath, most often from the VIII cranial nerve. Extracranially, 25% of all schwannomas are located in the head and neck. Intra-oral development is uncommon and a location in the tongue has been reported in individual cases.

METHODOLOGY

We present a young patient with a schwannoma in the distal right side of the tongue.

RESULTS

The tumour had grown slowly producing no symptoms. The diagnosis was made on histological examination. Surgical enucleation of the mass was uncomplicated and there was no recurrence.

CONCLUSIONS

We report a further case of a schwannoma of the tongue, highlighting the need for this to be considered in the differential diagnosis.

Pediatric middle ear infections and gastroesophageal reflux

OBJECTIVES

The pathogenesis of middle ear infections in children is multifactorial and includes infection, anatomical factors, impaired immunologic status, allergy, familial predisposition, male sex, method of feeding and environmental factors. Glue ear remains the commonest cause of deafness in childhood. Gastroesophageal reflux (GOR) is a common problem in the newborn and preschool periods. Recent research suggests that it may be related to eustachian tube dysfunction and otitis media.

METHODS

We review the literature and discuss the possible relationship between Gastroesophageal reflux and otitis media in children.

CONCLUSIONS

The current data are not enough to support antireflux treatment in children with refractory middle ear infections. More prospective randomised placebo-controlled studies are needed.

Expression patterns of cyclins D1, E in laryngeal epithelial lesions: correlation with other cell cycle regulators (p53, pRb, Ki-67 and PCNA) and clinicopathological features

The expression of cell-cycle progression molecules cyclin D1 and cyclin E were immunohistochemically examined in a series of 64 squamous cell invasive carcinomas of the larynx, 10 in situ carcinomas, 34 cases of dysplasia, 11 papillomas and 23 cases of keratosis. The results of their expression were compared with two cell-cycle implicated tumor suppressor proteins p53 and pRb as well as with two proliferation associated indices PCNA and Ki-67 in an attempt to elucidate their potential role in the pathogenesis and progression of these lesions. Nuclear staining for cyclin D1 and E (>5% positive cells) was observed in 19% and 39.7% of the laryngeal carcinomas, respectively. Significantly elevated levels of cyclin D1 and E in invasive laryngeal carcinomas compared with in situ carcinomas were revealed (p=0.045 and p=0.0003, respectively). High levels of cyclin D1 and E expression were correlated with increased Ki-67 score (p=0.037 and 0.017 respectively). A significant positive correlation between cyclin D1 and E was also detected in carcinomas (p=0.018). Decreased levels of cyclins D1 and E in the group of in situ carcinomas compared with those of dysplastic cases and papillomas were also observed. In the dysplastic lesions cyclin D1 expression was correlated with pRb expression (p=0.02). In the cases of keratosis cyclins D1 and E expression were correlated with pRb (p=0.002 and p=0.036, respectively), while cyclin D1 was associated with PCNA (p=0.008) and Ki-67 score (p=0.009). The prognostic significance of cyclins D1, E in determining the risk of recurrence and overall survival with both univariate (long-rang test) and multivariate (Cox regression) methods of analysis showed no statistically significant differences. We conclude that the expression of cyclins D1 and E in squamous cell carcinomas of the larynx does not seem to have a prognostic significance. In addition, their expression may be involved in the development of laryngeal lesions, implicated in cell proliferation, with other cell cycle related proteins, probably by different molecular pathways.

The role of CD44 in the development and prognosis of head and neck squamous cell carcinomas

CD44, the product of a single gene, exists as several isoforms generated by alternative exon splicing and posttranslational modifications, and is widely distributed in different cells and tissues including those of squamocellular origin. CD44 is a cell surface glycoprotein involved in many cellular processes acting as a receptor for cell to cell or cell to matrix adhesion, as a signal transmitter and as a growth factor-presenting molecule. Numerous studies based on immunohistochemical analyses of paraffin-embedded or frozen tissue sections using different monoclonal antibodies to CD44 isoforms and molecular biological techniques have provided evidence that in many types of tumours there is overexpression of CD44 isoforms and aberrant processing of immature CD44 transcripts relative to non-neoplastic control tissues, suggesting a role of CD44 in tumour development and progression. In contrast to these malignancies, one or more of the CD44 splice-variant isoforms are down-regulated in squamous cell carcinomas of the head and neck. CD44-deficient mice develop normally without giving rise to spontaneous tumours, but CD44-negative cells appear to be more susceptible to oncogenic transformation. Reduction in the expression of CD44 may confer growth advantage and malignant properties to tumour cells. The clinical significance of CD44 in squamous cell carcinomas of the head and neck as a tumour marker for cancer diagnosis and prognosis is discussed.

Ramsay Hunt syndrome presenting as a cranial polyneuropathy

Ramsay Hunt syndrome (RHS) is herpes zoster of the facial nerve, frequently associated with VIII cranial nerve involvement, but on rare occasions other cranial nerves are affected as well. We present the case of a 63-year-old woman with RHS with involvement of V, VII, VIII, IX, and XII cranial nerves. The patient showed significant improvement after treatment with acyclovir and prednisolone. RHS should be recognized as a polycranial neuritis characterized by damage to sensory and motor nerves, including the facial nerve and the auditory-vestibular apparatus. Early institution of treatment with antiviral agents may help hasten healing. Involvement of the XIIth cranial nerve has not been reported previously.

Seromucous maxillary sinusitis (SMMS): a clinicophysiological approach

Chronic sinusitis, especially maxillary sinusitis is a common disorder in humans. Seromucous sinusitis is rarely described in the literature. The present study deals with the clinical and laboratory characteristics of a group of patients suffering from the above disorder. During the last 10 years, 32 patients suffering from seromucous maxillary sinusitis were enrolled in the study. Patients' charts were reviewed and tabulated according to age, sex, history, clinical symptoms and laboratory findings. Treatment was based on punction and drainage of the seromucous effluent. Results were also statistically evaluated. Flight trips and atypical episodes of nasal infection were the predisposing factors for seromucous maxillary sinusitis. The only clinical manifestation was coughing, for at least 12 weeks before diagnosis. Sinus effluent was composed by serous and mucous constituents with glue like structure. There were no differences between sexes in predisposing factors, or x-ray findings. The treatment is paracentesis and drainage and in one case of recurrence, middle meatotomy and sinus endoscopy.

Antiproliferative and anticarcinogenic effects of an aqueous preparation of Abies alba and Viscum album se abies, on a L-1210 malignant cell line and tumor-bearing Wistar rats

Extracts of plants have been widely tested for possible anticarcinogenic properties. In the present study a traditional remedy, consisting of an aqueous extract of mixed parts of the tree Abies alba and its mistletoe Viscum album se abies was tested on benzo(alpha)pyrene(BaP)-induced tumors in Wistar rats and on the L-1210 malignant cell line. Two main groups of male Wistar rats subcutaneously injected by 10 mg of BaP, a dose inducing 100% carcinogenesis, a control group (C-G, 15 rats) and a treatment group(TR-G, 18 rats), were used for the study. Five animals bearing BaP-induced tumors were also tested (TR-1-G). Animals of the TR-G were orally administered with the aqueous extract at doses of 50 ml/kg b.w, from the day of BaP injection and of the TR-1-G, from the 120th day of injection, till death. L-1210 malignant cells in cultivation, were administered with a powder obtained by condensation and lyophilization of the extract, at various concentrations and cytotoxicity was measured by the microculture tetrazolium assay. Autopsy of the rats, revealed metastasis in the lungs of the animals of all groups and the tumors developed were histologically identified as leiomyosarcomas. The results indicated that the extract of the above plants possess anticarcinogenic effects, documented by: a) its antiproliferative effects on L-1210 cells (IC50 = 49.6 +/- 1.4 micrograms/ml), b) the significant prolongation of life and reduction of tumor growth rate of the animals of the TR-G in comparison to the C-G, c) the inhibition by 16.6% of tumor induction in the TR-G and d) the prolongation of life and the necrotic effects of the extract on the tumors of the animals in the TR-1-G. The antiproliferative effects of the Abies alba and Viscum album se abies extract may be due to the lectins and thionins contained in Viscum album, as well as to the monoterpenes contained in Abies alba. Soft tissue tumors sensitive to the extract, are widespread among human organs, even in larynx, and are usually resistant to chemotherapy.

Prognostic significance of p53 in the cancer of the larynx

p53 is a nuclear phosphoprotein acting as a transcription factor to regulate cell cycle progression and apoptosis, mediated by a number of target genes. p53 mutant proteins have lost a) the ability to act as sequence-specific transcription factors and b) their tumour suppressive properties. As p53 is the most commonly mutated gene in human cancer, including laryngeal squamous cell carcinoma, an aggressive and most frequent tumour of head and neck, it has attracted a great deal of interest as a prognostic factor, diagnostic tool and therapeutic target. This article reviews the current understanding of the prognostic significance of p53 in laryngeal squamous cell carcinoma. Immunohistochemical staining techniques and molecular genetics demonstrated that p53 activation is an early event in laryngeal squamous cell carcinogenesis but can not be used as a reliable prognostic marker.

Surgery on the larynx and pharynx in Byzantium (AD 324-1453): early scientific descriptions of these operations

We present the techniques of various operations on the larynx and pharynx (incision of abscesses of the tonsils, tonsillectomy, tracheotomy, uvulectomy, and removal of foreign bodies) found in the Greek texts of Byzantine physicians. The techniques of these operations were the first to be so meticulously described and were compiled from the texts, now lost, of the ancient Greek physicians. These medical texts, which followed and enriched the Hippocratic, Hellenistic, Roman, and Galenic medical traditions, later influenced medieval European surgery, either directly through Latin translations or indirectly through works of Arab physicians.

Immunohistochemical expression of metallothionein in benign premalignant and malignant epithelium of the larynx: correlation with p53 and proliferative cell nuclear antigen

In this study we evaluated the immunohistochemical expression of metallothionein (MT) in 44 squamous cell carcinomas, 14 cases of in situ carcinoma, 47 with epithelial dysplasia, 11 papillomas and 21 cases of keratosis. The MT expression was studied in correlation with p53 protein expression and the proliferative cell nuclear antigen (PCNA). The monoclonal antibodies E9 (anti-MT), DO-7 (which reacts with a denaturation-resistant epitope in wild-type and mutant p53) and PC10 (anti-PCNA) on formalin-fixed, paraffin-embedded tissue were used employing the immunoperoxidase (ABC) method. The immunohistochemical localization of MT has shown its rather ubiquitous presence in the cytoplasm and nucleus of both benign and malignant epithelial cells. In most cases the adjacent "normal" epithelium showed low positivity in the basal portion. The mean value of metallothionein expression was 35.73 in squamous cell carcinomas, 32.21 in in situ carcinomas, 11.86 in dysplastic epithelium, 5.10 in papillomas and 3.5 in keratosis. In carcinomas, low MT expression (< 10% of neoplastic cells) was observed in 20.5% of the cases, moderate (10%-50% of neoplastic cells) in 54.5% and extensive expression (> 50% of neoplastic cells) in 25% of the cases. We did not find any statistically significant difference of MT expression between in situ and infiltrating carcinomas, while we did observe a significant difference between carcinomas and the other groups. There was a statistically significant difference in the PCNA values in both benign and malignant lesions, while no statistically significant difference was observed in p53 protein expression in the above groups. A positive correlation between MT expression and the PCNA value (p < 0.0001) in the benign and malignant groups was detected. The PCNA value was also correlated with the p53 protein expression (p = 0.001). No correlation was found between MT and p53 protein expression. In conclusion, these results suggest that the MT expression may play a role in the development of malignant disease of the larynx, from the early phase of laryngeal carcinogenesis, independently from the p53 expression. It is also possible to contribute to tumour cell growth, as determined by the PCNA score.

Testicular tumor metastatic to the nose. A case report

In this paper we present an uncommon tumor found in the nasal cavity, the result of a metastasis from primary tumor of testis (embryonal carcinoma) in a young patient of 24 years of age. For this uncommon tumor we discuss the case with the Greek and foreign bibliography.

Glycoprotein CD44 expression in benign, premalignant and malignant epithelial lesions of the larynx: an immunohistochemical study including correlation with Rb, p53, Ki-67 and PCNA

CD44 is an integral membrane glycoprotein that has diverse functions in cell-cell and cell-substrate interactions. It has been suggested that it may be a determinant of metastatic and invasive behavior in carcinomas. The immunohistochemical expression of CD44 was examined in a series of 34 squamous cell carcinomas, 13 in situ carcinomas, 35 cases with various degrees of epithelial dysplasia, 10 papillomas and 17 cases of keratosis. We used the monoclonal mouse anti-human phagocytic glycoprotein-1 CD44 (clone DF 1485), on formalin-fixed, paraffin-embedded tissue. CD44 expression was correlated with the expression of Rb and p53 proteins, with the proliferative indices Ki-67 and PCNA as well as with conventional clinicopathological data. The mean value of CD44 expression was 78.84 in squamous cell carcinomas, 78.04 in situ carcinomas, 54.93 in dysplasia, 26.8 in papillomas and 24.97 in keratosis. There was no significant difference of CD44 expression between in situ and invasive carcinomas. However, a strong difference of reaction between carcinomas and the other cases was observed. CD44 expression was statistically higher in dysplastic lesions than the cases of keratosis (p < 0.0001) and papillomas (p = 0.01). In the group of invasive carcinomas, CD44 expression was statistically correlated with pRb (p = 0.011), while in preinvasive lesions it was correlated with PCNA (p = 0.016). The relationship with the degree of dysplasia or grade of carcinoma and p53 protein expression was insignificant. These observations suggest that CD44 expression may be involved in the multiple mechanism of the development and progression of laryngeal lesions and may help to predict the risk of transformation of the benign or precancerous lesions to cancer.

Immunohistochemical expression of cathepsin D in laryngeal epithelial lesions: correlation with CD44 expression, p53 and Rb status and proliferation associated indices

Clinical studies in several tumour types have shown a strong correlation between cathepsin D expression and tumour progression. Immunohistochemical staining for cathepsin D (clone D13A) was performed in paraffin embedded-tissues from 39 invasive squamous cell carcinomas, 13 in situ carcinomas, 35 cases of dysplasia, 10 papillomas and 17 cases of keratosis. The association between cathepsin D expression and CD44, p53, Rb proteins and proliferation indices (Ki-67, PCNA) was assessed by univariate analysis. Cathepsin D was highly positive in the groups of carcinomas compared to other lesions (p < 0.0001). A statistically significant correlation of cathepsin D expression with CD44 expression was observed in invasive cancers (p = 0.037). The relationship of cathepsin D immunoreactivity with p53, Rb and proliferation indices was insignificant. The results show that cathepsin D is expressed in a higher proportion of cancerous lesions of the larynx than in non cancerous or premalignant lesions, a fact which suggests that cathepsin D may be involved in laryngeal tumour cell growth process.

From the roots of otology: diseases of the ear and their treatment in Byzantine times (324-1453 A.D.)

HYPOTHESIS

The aim of this study is to present the therapeutic methods and surgical techniques in diseases of the ear during Byzantine times (324-1453 A.D.).

BACKGROUND/METHODS

The original Greek language texts of the Byzantine medical writers were studied to research early otologic knowledge of symptomatology, conservative treatments, and surgical confrontation of diseases of the ear.

RESULTS

A considerable number of conservative treatments for many otologic conditions were identified; these therapies were especially based on herbs, animal and mineral substances applied either as eardrops, clysters, poultices, or by using special instruments and apparatus. Among these were identified otitis, rupture of the eardrum, hemorrhage from the ears, deficiency of hearing and deafness, vertigo, tinnitus, and earwax. Furthermore, in these early texts, there were also described some surgical techniques in cases of atresia of the external auditory canal, of defects in or lack of the pinna, and for removal of foreign bodies and fleshy tumors. Some of the earliest hearing aids were also mentioned.

CONCLUSIONS

From the study of the original works of Byzantine writers, it is evident that numerous treatments and surgical techniques relating to otology were practiced; these were derived not only from compilation of knowledge obtained from the ancient Greek medical sources, a considerable part of which are now lost, but also enriched by Byzantine physicians' personal experience. This knowledge influenced medieval European medicine and, through it, that of the rest of the world.

Altered patterns of retinoblastoma gene product expression in benign, premalignant and malignant epithelium of the larynx: an immunohistochemical study including correlation with p53, bcl-2 and proliferating indices

In order to study the altered Rb, bcl-2 and p53 proteins expression during laryngeal carcinogenesis and to elucidate the role of these molecules in the development and progression of the lesions, we have examined the immunohistochemical expression of these markers in a series of 41 squamous cell carcinomas, 14 cases of in situ carcinoma, 47 with epithelial dysplasia, 11 papillomas and 20 cases of keratosis. Rb protein was expressed in 69.7% (> 5% positive neoplastic cells) of squamous cell carcinomas and p53 in 40% (> 5% positive cells). There was a strong statistically significant difference for Rb, Ki-67 and PCNA immunostaining between malignant, premalignant and benign lesions, increasing from keratosis, papillomas, dysplasia to carcinoma in situ or infiltrating squamous Ca. Rb protein expression was also strongly correlated with p53, Ki-67 and PCNA, while p53 protein was strongly correlated with Ki-67 (p = 0023) and PCNA (p = 0.0031) indices, in all lesions. In conclusion Rb and p53 altered proteins expression seems to play an active role in laryngeal carcinogenesis, probably from the early phase, and is correlated with proliferative activity. Also, Rb protein expression is correlated with the progression of the lesion and could be considered as indication of poor prognosis in laryngeal lesions.

[Our experience with parotid cysts]

The cysts of the parotid gland are very rare lesions of congenital or acquired aetiopathogenesis. In most cases, the symptom is an unilateral painless swelling in the area of the parotid without any fixation to the overlying skin or any involvement of the facial nerve. These must be distinguished from neoplasms with a similar clinical presentation or neoplasms with a cystic component. Making the right preoperative diagnosis can be extremely difficult but the adequate therapy remains the superficial parotidectomy. However the final diagnosis is established histopathologically. The precise histological classification is often an elaborate task because of the similarities in the epithelial lining of the various cysts and the heterogeneity in their histogenic origin. In this study, the authors describe four cases of parotid cystis. They examine the clinical aspects, the preoperative diagnostic approach, the treatment and they analyse the histopathological findings. Finally, their results are compared with the data found in the international medical literature.

Comparative study of evoked electromyography and facial nerve latency test in the prognosis of idiopathic facial nerve palsy in childhood

We report our results from the application of evoked electromyography (EEMG) and facial nerve latency testing (FNLT) in 30 children aged 4-14 years with idiopathic facial palsy. Our aim was to define the value of these tests as prognostic tools in Bell's palsy. From the EEMG results we ascertained that, when the amplitude of the compound muscle action potential varied between 51% and 95% of the normal value, the neuronal damage is slight (neurapraxia). When the percentage value of muscle response decreases, the prognosis is worse. The results of the FNLT showed that, when the latency is within normal limits, the damage to the nerve is slight (neurapraxia). If the latency is prolonged, the prognosis is worse. Evaluation of our results and comparison with the index of facial nerve functional recovery showed that those two tests have a high percentage of correctness (100% for the EEMG and 96.7% for the FNLT) and a low percentage of error. We conclude that these tests are excellent for predicting the outcome of facial nerve palsy in childhood and we suggest that young patents undergo both so that the determination of the lesion may be as correct as possible.

[Our experiences with cerebrospinal fluid rhinorrhea and its surgical treatment using an extracranial approach]

The cerebrospinal fluid rhinorrhea is usually due to a skull lesion and is potentially dangerous for the patient, as it can be followed by an ascending meningitis. The extracranial approach (external ethmoidectomy, osteoplasty of the frontal sinus) has substituted craniotomy, especially in cases where the cerebrospinal fluid rhinorrhea is not due to intracranial lesions. In this study, we describe the surgical treatment of 9 patients treated in our clinic, and we make a brief review of the literature.

Hearing loss and vestibular dysfunction in childhood from the use of streptomycin in Albania

With the entry of a large number of Albanians in the area of Epirus over the past 8 months, a significant number of children with hearing problems or deafness has been examined in the out patient ward of the University Hospital of Ioannina. From the Pediatric-Neurologic-Psychiatric and Otorhinolaryngologic examination of these children, 18 cases with hearing problems and vestibular dysfunction due to administration of streptomycin sulfate have been defined. This article reports the ototoxic drug which has been used and is still being used in Albania, the procedure of audiological and vestibular investigation, and the damage which has been evoked in the auditory and vestibular pathway of the children in whom it has been administered.

Perceptive bilateral deafness following clinical tetanus to a neonate

A rare case of bilateral perceptive deafness following clinical tetanus is reported. The patient was a 15-day-old neonate. The clinical tetanus was treated with tetanus antitoxin (human gamma globulins) and penicillin. The exact mechanism of auditory nerve damage associated clinical tetanus and treatment with human tetanus antitoxin and penicillin is still not clearly known. We believe that the damage of the hearing organ can be attributed to the tetanus toxin and not to the human gamma globulins (tetanus antitoxin).