The influence of passivation and electropolishing on the performance of medical grade stainless steels in static and fatigue loading

The effects of surface passivation and electropolishing on the mechanical performance of a group of biomedical grade stainless steels have been investigated. Surface roughness measurements showed that the treatments had a significant effect on the final surface finish. However, static mechanical testing demonstrated no difference in static mechanical properties, regardless of surface treatment. High cycle fatigue testing was carried out at a frequency of 120 Hz with a load ratio of R=0.1, in both air and a simulated in vivo wet corrosive environment. 316LVM (cold worked) proved superior to 316L (annealed) in fatigue performance, in both dry and wet environments. The fatigue performance of both materials did depend on the surface treatment, with electropolishing resulting in better performance than passivation. The fatigue performance of both materials was significantly better in the dry environment in comparison to the wet environment. The dry-to-wet deterioration in fatigue performance was somewhat dependent on the surface treatment for the 316L material but almost independent of surface treatment for the 316LVM material. Significant surface pitting and damage was evident for 316L during fatigue in the wet environment, whereas almost no pitting and damage was observed for 316LVM.

Clinical experience with HLA-B7 plasmid DNA/lipid complex in advanced squamous cell carcinoma of the head and neck

OBJECTIVE

To investigate the safety and efficacy of alloantigen plasmid DNA therapy in patients with advanced head and neck squamous cell carcinoma using Allovectin-7 (Vical Inc, San Diego, Calif), a DNA/lipid complex designed to express the class I major histocompatibility complex antigen HLA-B7.

DESIGN

Multi-institutional prospective trial.

SETTING

Academic medical setting.

PATIENTS

A total of 69 patients were enrolled in 3 sequential clinical trials: a single-center phase 1 trial and 2 multicenter phase 2 trials. Eligibility criteria included unresectable squamous cell carcinoma that failed conventional therapy, Karnofsky performance status score of 70 or greater, and no concurrent anticancer or immunosuppressive therapies.

INTERVENTION

Patients received 2 biweekly intratumoral injections of 10 microg (phase 1 and first phase 2 trials) or 100 microg (second phase 2 trial) of Allovectin-7 followed by 4 weeks of observation. Patients with stable or responding disease after the observation period were given a second treatment cycle identical to the first.

MAIN OUTCOME MEASURES

Patients were assessed for toxic effects, and tumor size was measured after cycles 1 (at 6 weeks) and 2 (at 16 weeks).

RESULTS

Allovectin-7 treatment was well tolerated, with no grade 3 or 4 drug-related toxic effects. Of 69 patients treated, 23 (33%) had stable disease or a partial response after the first cycle of treatment and proceeded to the second cycle. After the second cycle, 6 patients had stable disease, 4 had a partial response, and 1 had a complete response. Responses persisted for 21 to 106 weeks.

CONCLUSIONS

Intratumoral plasmid DNA immunotherapy for head and neck cancer with Allovectin-7 is safe, and further investigations are planned in patients with less advanced disease, where it could potentially improve patient survival and reduce the need for radical high-morbidity treatments.

GSLII positivity is not confined to oligodendrocytes in adult mammalian CNS

The in vivo binding pattern of the lectin Griffonia simplicifolia II (GSLII) was evaluated in sections of adult cat optic nerve following reports that it is a marker for oligodendrocytes in adult rodent CNS and that it may also be an oligodendroglial lineage marker. Following as closely as possible the immunocytochemical methodology employed in these reports, staining for GSLII was incorporated into sets of consecutive one micron thick sections comprising known cell-type specific reference markers backed up by electron microscopy. With this correlative protocol both lectin positive and lectin negative cells could be reliably identified. The material examined included normal control tissue and tissue containing previously studied demyelinating lesions of various ages in which oligodendrocyte progenitors and precursors have been characterized. GSLII was found to stain not only mature oligodendrocytes in adult cat optic nerve but also activated microglia, macrophages, polymorphonuclear leucocytes and other haematogenous cells. Lectin positivity was not found in oligodendroglial precursors, endothelial cells, astrocytes or ramified microglia. This study emphasises that care needs to be taken before assigning lineage marker status to individual lectins or antibodies.

Functional results of primary closure vs flaps in oropharyngeal reconstruction: a prospective study of speech and swallowing

BACKGROUND

The preservation of speech and swallowing function is the primary goal when reconstructing soft tissue defects in the oral cavity or oropharynx. The type of reconstructive procedure used should be based on outcome data examining speech and swallowing function; yet, there is a paucity of such information.

OBJECTIVES

To present the results of a multi-institutional prospective study of speech and swallowing function before and after soft tissue reconstruction of the oral cavity and oropharynx, and to compare 3 methods of reconstruction with respect to speech and swallowing function: primary closure, distal myocutaneous flap, and microvascular free flap.

DESIGN

Prospective case-comparison study.

SETTING

Four leading head and neck cancer institutions.

PATIENTS

The patients were selected from a database of 284 patients treated at the different institutions. The patients were matched for the location of the oral cavity or oropharyngeal defect and the percentage of oral tongue and tongue base resection. Those patients who had previous speech and swallowing deficits and patients in whom postoperative fistulas or wound infections developed were excluded from the study.

METHODS

The patients underwent speech and swallowing evaluation preoperatively and 3 months after healing. This evaluation included videofluoroscopic studies of swallowing and tests of speech intelligibility and sentence articulation. Videofluoroscopy provided measures of swallowing efficiency and bolus movement. Liquid and paste consistencies were used in evaluating swallowing function.

MAIN OUTCOME MEASURE

The functional results of the reconstruction.

RESULTS

Patients who had primary closure were more efficient at swallowing liquids, had less pharyngeal residue, a longer oral transit time with paste, and higher conversational intelligibility than patients who underwent reconstruction with a distal flap. Compared with patients who underwent reconstruction with a free flap, those who had primary closure had more efficient swallowing of liquids, less pharyngeal residue, and shorter pharyngeal delay times with paste. No difference in the speech and swallowing function existed between patients treated with distal myocutaneous flaps and those treated with microvascular free flaps.

CONCLUSION

Contrary to the current theory of oral and oropharyngeal reconstruction, we found that the use of primary closure resulted in equal or better function than the use of flap reconstruction in patients with a comparable locus of resection and percentage of oral tongue and tongue base resection.

Planned early neck dissection before radiation for persistent neck nodes after induction chemotherapy

Optimal management of advanced neck metastases as part of an organ preservation treatment approach for head and neck squamous carcinoma (HNSC) is unclear. Since 1989, our management paradigm for patients on organ preservation was modified to incorporate planned early neck dissection before radiation therapy for patients who did not achieve a complete response (CR) of neck nodes after induction chemotherapy (IC). The purpose of this study was to determine if planned early neck dissection is a safe and effective approach in the management of advanced nodal disease as part of organ preservation. Fifty-eight consecutive patients with advanced HNSC who were entered in organ preservation trials using induction chemotherapy and radiation with surgical salvage were studied. Median follow-up was 26 months. Of the 58 patients, 71% were stage IV. Patients were grouped by nodal response to chemotherapy and N class, and were analyzed with respect to patterns of recurrence, complications, and survival. Overall, the rate of CR of neck nodes was 49%. Fifty-one percent had less than a complete response of neck nodes after IC and required planned early neck dissection. There were no significant differences in patterns of recurrence, complications, interval time to start of radiation, recurrence, or survival rates between the CR and less than CR groups. These data suggest that planned early neck dissection for patients with less than CR in the neck after IC is not detrimental with respect to neck relapse or overall survival. We believe that planned early neck dissection can be safely incorporated into future organ preservation treatment protocols for patients with advanced head and neck carcinoma.

CaN19 expression in benign and malignant hyperplasias of the skin and oral mucosa: evidence for a role in regenerative differentiation

CaN19, a member of the S100 family of calcium-binding proteins, is known to be "underexpressed" in cultured breast carcinoma-derived cell lines relative to their normal counterparts. By Northern blotting, we confirm these results and find that CaN19 is also markedly "underexpressed" in several carcinoma-derived cell lines of the skin, oral mucosa, and urogenital tract. However, exceptions to the inverse correlation between CaN19 expression and malignancy have been identified, bringing into question the hypothesis that CaN19 functions as a tumor suppressor gene. Unexpectedly, CaN19 mRNA was strongly expressed in bulk specimens of basal and squamous cell carcinomas of the skin and oral cavity. However, in situ hybridization revealed only limited CaN19 expression in tumor cells themselves; the bulk of expression is localized to hyperplastic perilesional epidermis. Tumor cell expression of CaN19 was similar in primary and locally metastatic tumors, indicating that this gene is not necessarily down-regulated during tumor progression. Coordinate overexpression of CaN19 and the "hyperproliferalive" keratin K6a was observed only in tissues undergoing squamous differentiation. Taken together with other recent results from our laboratory, these findings suggest the hypothesis that CaN19 participates in an epidermal growth factor receptor-dependent pathway of regenerative squamous differentiation.

Molecular genetics of Leber's hereditary optic neuropathy: study of a six-generation family from Western Australia

Molecular genetic studies were carried out on a 6-generation family from Western Australia with Leber's hereditary optic neuropathy. Pedigree analysis confirms the maternal inheritance of the genetic lesion underlying the disorder in this family. The presence of a recently reported disease-associated mutation at nucleotide 11778 of the mtDNA was established in one clinically affected family member by the sequencing of an appropriate 1.6 kb PCR-amplified fragment of the mtDNA; this mutation leads to an Arg340----His amino acid replacement in the ND4 subunit of respiratory complex I. The 11778 G to A base substitution is associated with the loss of an SfaNI restriction site. Examination of the representative members for this site revealed that while only mtDNA carrying this substitution could be detected in the leukocytes of 4 family members of the sixth generation, the mutated mtDNA was found to co-exist with the normal mtDNA population (heteroplasmy) in a clinically unaffected member from the fifth generation. This observation suggests that the nt 11778 mutation observed in this LHON family is relatively new; the observation of both heteroplasmy and apparent homoplasmy of the mtDNA in different family members might reflect the normal progression in the establishment of a mitochondrially inherited mutation.

Drug and alcohol abuse in patients with acute burn injuries

We reviewed records of adult patients admitted to our burn unit who were reported to abuse drugs or alcohol from 1985 to 1988. The proportion of patients reported as abusing drugs increased significantly from 1987 to 1988, compared to previous years. However, there was no increase in the proportion of patients reported to abuse alcohol. Patients identified as abusing drugs had longer hospital stays, compared to patients who were not reported to abuse substances. Methamphetamine and cocaine were the drugs most often abused by patients who abused drugs or both drugs and alcohol. Mechanisms of burn injury in these patients included "accidental" burn injury related to acute intoxication, and self-injury due to psychosis or depression.

Cytotoxic T lymphocytes specific for self tumor immunoglobulin express T cell receptor delta chain

CTL are thought to play a role in the elimination of transformed cells in vivo. The effectiveness of such CTL is in part dependent on recognition of tumor specific antigens. Among the best characterized tumor-specific antigens are the unique or idiotypic determinants on the Ig of B cell lymphomas. Here we describe the generation and properties of human CTL specific for the idiotype on autologous B cell tumors. These cells are CD3+,CD4-,CD8- and express the delta chain of the TCR. Such cells may prove useful in tumor-specific adoptive therapy.

Preexisting psychiatric disorders in burn patients

The authors studied 51 of 56 consecutive eligible patients admitted to a burn unit. Sixty-nine percent of the patients had a preburn psychiatric diagnosis. Depression alone was present in more than half the sample. Few burns were strictly accidental; 68% involved some degree of complicity on the victim's part, but intentional burns were rare. Patients with depression were more likely to sustain their burns in a setting of risk-enhancing behavior.

Idiotype vaccination against murine B cell lymphoma. Humoral and cellular responses elicited by tumor-derived immunoglobulin M and its molecular subunits

C3H/HeN mice were immunized with idiotypic immunoglobulin M (IgM) and its molecular subunits from the syngeneic 38C13 lymphoma. Immunization with idiotypic IgM (38C-Id) resulted in idiotype-specific humoral and cellular immunity and protection against a lethal tumor cell challenge. Heavy (H38C) and light (L38C) chains were isolated by electroelution from preparative polyacrylamide gels. Both of these immunogens induced significant resistance to a subsequent tumor challenge. Variable region immunogens, in the form of trpE-fusion proteins, were obtained by cloning heavy and light chain variable region genes into the expression plasmid pATH-11. Of these, only the trpE-VH38C immunogen yielded immune resistance to tumor challenge. Finally, the nucleic acid sequence of 38C-Id light chain was determined and, based on the corresponding amino acid sequence and an analysis of predicted secondary structure, a region of potential antigenicity in complementarity-determining region 3 was chosen for the production of a synthetic peptide. Vaccination with this synthetic peptide resulted in significant suppression of tumor growth. Analysis of the humoral and cellular immunity generated by these vaccines revealed the presence of antibodies reactive with native idiotypic IgM only in 38C-Id, H38C, and trpE-VH38C immune sera, although the latter two were not idiotype-specific. Idiotype-specific lymphocytes, which proliferated in response to native 38C-Id, were observed in all immune animals. With the exception of the fusion protein immunogens, conjugation to an immunogenic carrier protein (keyhole limpet hemocyanin or thyroglobulin) was required for optimal humoral and cellular responses.

Idiotype vaccination against murine B cell lymphoma. Humoral and cellular responses elicited by tumor-derived immunoglobulin M and its molecular subunits

C3H/HeN mice were immunized with idiotypic immunoglobulin M (IgM) and its molecular subunits from the syngeneic 38C13 lymphoma. Immunization with idiotypic IgM (38C-Id) resulted in idiotype-specific humoral and cellular immunity and protection against a lethal tumor cell challenge. Heavy (H38C) and light (L38C) chains were isolated by electroelution from preparative polyacrylamide gels. Both of these immunogens induced significant resistance to a subsequent tumor challenge. Variable region immunogens, in the form of trpE-fusion proteins, were obtained by cloning heavy and light chain variable region genes into the expression plasmid pATH-11. Of these, only the trpE-VH38C immunogen yielded immune resistance to tumor challenge. Finally, the nucleic acid sequence of 38C-Id light chain was determined and, based on the corresponding amino acid sequence and an analysis of predicted secondary structure, a region of potential antigenicity in complementarity-determining region 3 was chosen for the production of a synthetic peptide. Vaccination with this synthetic peptide resulted in significant suppression of tumor growth. Analysis of the humoral and cellular immunity generated by these vaccines revealed the presence of antibodies reactive with native idiotypic IgM only in 38C-Id, H38C, and trpE-VH38C immune sera, although the latter two were not idiotype-specific. Idiotype-specific lymphocytes, which proliferated in response to native 38C-Id, were observed in all immune animals. With the exception of the fusion protein immunogens, conjugation to an immunogenic carrier protein (keyhole limpet hemocyanin or thyroglobulin) was required for optimal humoral and cellular responses.