Does the use of a "wrap" in three-dimensional surgical planning influence the bony margin status of benign and malignant neoplasms of the oral, head, and neck region? An initial investigation

PURPOSE

Three-dimensional surgical planning (3-DSP) is becoming commonplace in the management of benign and malignant disease for oral and maxillofacial surgery practice within the last decade. Surgeons utilize a virtual "wrap" to preoperatively delineate and define maxillofacial tumor resection margins. The investigators hypothesized that the use of a wrap is a predictable method to obtain negative bony margins.

METHODS

The investigators implemented a retrospective chart review. The sample was composed of patients over the age of 18 treated at John Peter Smith Health Network and Parkland/UT Southwestern Medical Center who obtained 3-DSP for the pathology of the head and neck, involving the bone, with a virtual wrap utilized for bony margins. The proportion of cases was calculated, descriptive statistics were reported, and binomial exact calculation was performed for confidence intervals. The primary variable analyzed was bony margin status on final histopathology, involved or uninvolved, based on the pathology report.

RESULTS

The sample was composed of 39 cases, one of which was excluded due to aborting the preplanned 3-DSP. Of the 38 included cases, one had involved bony margin on final histopathology (2.6%; 95% confidence limits, 0.1%, 13.8%). There were 16 malignant cases (42%) and 22 benign cases (58%). When stratified by pathology, 1 out of the 16 malignant cases (6.3%; 95% confidence interval, 0.2%, 30%) and 0 out of the 22 benign cases (95% confidence interval, 0%, 15.4%) had an involved bony margin on final histopathology.

CONCLUSION

The results of this preliminary study suggest three-dimensional surgical planning with wrap margins is a predictable method to obtain negative bony margins in benign and malignant disease of the maxillofacial complex. Further studies will focus on compiling prospective data to solidify the accuracy and predictability of using a wrap to obtain negative bony margins.

Abstract 3056: Characteristics and outcomes of patients with hepatocellular carcinoma diagnosed at John Peter Smith Hospital

Background: The incidence of hepatocellular carcinoma (HCC) is increasing in the US, particularly in individuals infected with hepatitis C (HCV). Although early detection is crucial for better outcomes, at present, there is conflicting evidence regarding HCC screening and its reduction on cancer-related mortality. This study aimed to determine overall survival, prognostic factors influencing survival, and the effects of screening at-risk patients on HCC-related mortality.

Methods: A retrospective chart review of patients diagnosed with HCC from 1/1/2018 to 6/4/2021 for the one-year survival analysis and 6/4/2019 for the three-year analysis. Person-time was calculated as the days from the date of diagnosis until the last known encounter or death. The primary exposure of interest was screening within two years prior to the diagnosis date via ultrasound, MRI, and/or CT. Potential covariates were age at diagnosis, race/ethnicity, gender, insurance status, alcohol use disorder, HCV, HBV, and cirrhosis. Kaplan Meier, log rank test, and Cox proportional hazards (CPH) model were used to assess survival curves, survival distributions across screening status, and the effects of additional covariates on prognosis at one and three years, respectively. A backwards stepwise regression was used on the covariates identified via a pre-univariate filtering to construct a multivariable model.

Results: There were 165 and 71 patients who met the one- and three- year inclusion criteria, respectively. Survival at one and three years was 38% and 14%, respectively. Median survival for the 165 patients was 265 days (95% CI: 166, 337). Overall, 36% (n=59/163; 2 missing) and 27% (n=19/70; 1 missing) were screened prior to diagnosis. The CPH model showed a statistically significant difference in hazard ratio of death in the first year for those without screening compared to patients with screening (HR: 1.9; 95% CI: 1.2, 3.0; p-value: 0.005). After adjusting for race/ethnicity and insurance type, the CPH model yielded similar results (HR: 2.2; 95% CI: 1.3, 3.6; p-value: 0.002). The CPH model showed a statistically significant difference in hazard ratio of death in three years for those without screening compared to patients with screening (HR: 3.4; 95% CI: 1.7, 7.1; p-value: 0.001). After adjusting for gender, HBV, and race/ethnicity, the CPH model yielded similar results (HR: 2.2; 95% CI: 1.2, 4.0; p-value: 0.009).

Conclusion: Overall survival in patients diagnosed with HCC at JPS, a safety-net hospital, is similar to national statistics. Screening in patients at-risk for HCC shows improved survival at one and three years. Further evaluation based on the extent of disease at the time of diagnosis, treatment decisions, and type/timing of screening could be beneficial in determining the outcomes in HCC patients.

Citation Format: Madison Hull, Kari Teigen, Jolonda Bullock, Riyaz Basha, Kalyani Narra. Characteristics and outcomes of patients with hepatocellular carcinoma diagnosed at John Peter Smith Hospital [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3056.

Evaluating Changes in Family Medicine Applicant Characteristics Following the Onset of Virtual Interviewing

Background and Objectives: The COVID-19 pandemic obliged the field of graduate medical education to pivot from in-person to virtual residency interviews in 2020. The decreased travel and financial barriers of this format could potentially lead to greater diversity and equity in the primary care workforce. We aimed to evaluate changes in applicant pools from in-person to virtual interviewing cycles. Methods: We conducted a retrospective review of Electronic Residency Application Services (ERAS) from five US family medicine residencies across five interview cycles (three in-person and two virtual; 2017/2018 through 2021/2022). We compared geographic and demographic data about applicants as well as administrative program data. Results: The study included 25,271 applicants. The average distance between applicants and programs was 768 miles during in-person interview years and 772 miles during virtual interview years (P=.27). Applicants who interviewed with programs were 446 and 459 miles away, respectively (P=.06). During in-person application years, applicants with backgrounds historically underrepresented in medicine (URM) submitted an average of 21% of applications; this increased approximately 1% during virtual interviewing years (OR, 1.08; P=.03). There were no other differences between in-person and virtual application years in rates of URM applicants. Residency programs received more applications from US medical schools (OR, 1.46; P<.0001) and were more likely to interview a US medical school applicant (OR, 2.26; P<.0001) in virtual years. Program fill rates appeared to be lower during virtual years. Conclusions: The virtual interviewing format did not appear to substantially increase the geographic, racial, or ethnic diversity of applicants, and was associated with increased applications from US medical schools.

Implementation of a Preoperative Huddle at a Level 1 Trauma Center

OBJECTIVE

Medical errors resulting in patient harm still occur at an alarmingly high rate. Surgery is a high-risk area that can frequently result in patient harm if errors occur. There is a need for standardization of communication and processes to decrease errors. We sought to determine whether the implementation of a preoperative huddle at our hospital could standardize communication and decrease medical errors.

METHODS

A unique preoperative huddle was developed and implemented at a level 1 trauma center. We reviewed data before and after the implementation of the preoperative huddle including patient surveys and comments, the percentage of on-time operating room (OR) starts, OR turnover times, and the number of sentinel events.

RESULTS

After huddle implementation, we observed a trend of improvement in our patient survey results on patient's perception that the doctors/nurses explained the procedure understandably after huddle implementation. There was a statistically yet limited clinically significant increase in OR turnover time from 37 to 40 minutes (P < 0.001). There was also an increase in on-time OR starts from 37% to 45% (P < 0.001). We observed a decrease in the number of sentinel events, with only 1 occurring each year since implementation.

CONCLUSIONS

A preoperative huddle was successfully implemented at a level 1 trauma hospital and helped standardize communication without significantly disrupting workflow. To our knowledge, this method of preoperative huddling has not been previously described in the literature.

Conformation of the substrate and pterin cofactor bound to human tryptophan hydroxylase. Important role of Phe313 in substrate specificity

Tryptophan hydroxylase (TPH) carries out the 5-hydroxylation of L-Trp, which is the rate-limiting step in the synthesis of serotonin. We have prepared and characterized a stable N-terminally truncated form of human TPH that includes the catalytic domain (Delta90TPH). We have also determined the conformation and distances to the catalytic non-heme iron of both L-Trp and the tetrahydrobiopterin cofactor analogue L-erythro-7,8-dihydrobiopterin (BH2) bound to Delta90TPH by using 1H NMR spectroscopy. The bound conformers of the substrate and the pterin were then docked into the modeled three-dimensional structure of TPH. The resulting ternary TPH-BH2-L-Trp structure is very similar to that previously determined by the same methods for the complex of phenylalanine hydroxylase (PAH) with BH2 and L-Phe [Teigen, K., et al. (1999) J. Mol. Biol. 294, 807-823]. In the model, L-Trp binds to the enzyme through interactions with Arg257, Ser336, His272, Phe318, and Phe313, and the ring of BH2 interacts mainly with Phe241 and Glu273. The distances between the hydroxylation sites at C5 in L-Trp and C4a in the pterin, i.e., 6.1 +/- 0.4 A, and from each of these sites to the iron, i.e., 4.1 +/- 0.3 and 4.4 +/- 0.3 A, respectively, are also in agreement with the formation of a transient iron-4a-peroxytetrahydropterin in the reaction, as proposed for the other hydroxylases. The different conformation of the dihydroxypropyl chain of BH2 in PAH and TPH seems to be related to the presence of nonconserved residues, i.e., Tyr235 and Pro238 in TPH, at the cofactor binding site. Moreover, Phe313, which seems to interact with the substrate through ring stacking, corresponds to a Trp residue in both tyrosine hydroxylase and PAH (Trp326) and appears to be an important residue for influencing the substrate specificity in this family of enzymes. We show that the W326F mutation in PAH increases the relative preference for L-Trp as the substrate, while the F313W mutation in TPH increases the preference for L-Phe, possibly by a conserved active site volume effect.

A kinetic and conformational study on the interaction of tetrahydropteridines with tyrosine hydroxylase

Tetrahydropterins are obligatory cofactors for tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine biosynthesis. A series of synthetic analogues of 6(R)-L-erythro-5,6,7, 8-tetrahydrobiopterin (BH(4)) with different substituents in positions C2, N3, C4, N5, C6, C7, and N8 on the ring were used as active site probes for recombinant human TH. The enzyme tolerates rather bulky substituents at C6, as seen by the catalytic efficiency (V(max)/K(m)) and the coupling efficiency (mol of L-DOPA produced/mol of tetrahydropterin oxidized) of the cofactors. Substitutions at C2, C4, N5, and N8 abolish the cofactor activity of the pterin analogues. Molecular docking of BH(4) into the crystal structure of the catalytic domain of ligand-free rat TH results in complexes in which the pteridine ring pi-stacks with Phe300 and the N3 and the amino group at C2 hydrogen bonds with Glu332. The pteridine ring also establishes interactions with Leu294 and Gln310. The distance between C4a in the pteridines and the active site iron was 4.2 +/- 0.5 A for the ensemble of docked conformers. Docking of BH(4) analogues into TH also shows that the most bulky substituents at C6 can be well-accommodated within the large hydrophobic pocket surrounded by Ala297, Ser368, Tyr371, and Trp372, without altering the positioning of the ring. The pterin ring of 7-BH(4) shows proper stacking with Phe300, but the distance between the C4a and the active site iron is 0.6 A longer than for bound BH(4), a finding that may be related to the high degree of uncoupling observed for 7-BH(4).

The structural basis of the recognition of phenylalanine and pterin cofactors by phenylalanine hydroxylase: implications for the catalytic mechanism

Phenylalanine hydroxylase (PAH) is a tetrahydrobiopterin and non-heme iron-dependent enzyme that hydroxylates L-Phe to l-Tyr using molecular oxygen as additional substrate. A dysfunction of this enzyme leads to phenylketonuria (PKU). The conformation and distances to the catalytic iron of both L-Phe and the cofactor analogue L-erythro-7,8-dihydrobiopterin (BH2) simultaneously bound to recombinant human PAH have been estimated by (1)H NMR. The resulting bound conformers of both ligands have been fitted into the crystal structure of the catalytic domain by molecular docking. In the docked structure L-Phe binds to the enzyme through interactions with Arg270, Ser349 and Trp326. The mode of coordination of Glu330 to the iron moiety seems to determine the amino acid substrate specificity in PAH and in the homologous enzyme tyrosine hydroxylase. The pterin ring of BH2 pi-stacks with Phe254, and the N3 and the amine group at C2 hydrogen bond with the carboxylic group of Glu286. The ring also establishes specific contacts with His264 and Leu249. The distance between the O4 atom of BH2 and the iron (2.6(+/-0.3) A) is compatible with coordination, a finding that is important for the understanding of the mechanism of the enzyme. The hydroxyl groups in the side-chain at C6 hydrogen bond with the carbonyl group of Ala322 and the hydroxyl group of Ser251, an interaction that seems to have implications for the regulation of the enzyme by substrate and cofactor. Some frequent mutations causing PKU are located at residues involved in substrate and cofactor binding. The sites for hydroxylation, C4 in L-Phe and C4a in the pterin are located at a distance of 4.2 and 4.3 A from the iron moiety, respectively, and at 6.3 A from each other. These distances are adequate for the intercalation of iron-coordinated molecular oxygen, in agreement with a mechanistic role of the iron moiety both in the binding and activation of dioxygen and in the hydroxylation reaction.

In vitro activity of 9 antimicrobial agents against 177 strains of Haemophilus influenzae isolated from hospitalized patients

In vitro activity of 4 commonly used and 5 new antibiotics was examined against 177 strains of Haemophilus influenzae. All strains were collected from various sites in patients with clinical infections. The study confirms that several newer antibiotics are useful alternatives to older drugs, as measured by in vitro activity. Ciprofloxacin and ofloxacin were the most active agents, (MIC90 0.012 micrograms/ml and 0.05 micrograms/ml respectively), followed by aztreonam (MIC90 0.1 micrograms/ml) and cefuroxime (MIC90 0.8 micrograms/ml). A new macrolide, azithromycin (CP 62,993), was more active than erythromycin, MIC90 1.6 micrograms/ml vs 6.4 micrograms/ml. Beta-lactamase production was detected in 4.5% (8/177) of the strains. In vitro activity was the same against strains collected in 1985 and 1988. No increase in beta-lactamase production was recorded.

[Toxic shock syndrome without any relation to the use of tampons or staphylococcal infection]

Toxic shock syndrome is a generalized disease traditionally thought to be caused by toxinproducing strains of Staphylococcus aurus. The syndrome is characterized by fever, hypotension, erythema of the skin, erythematous desquamation and multiple organ involvement. We present a case where the causative agent was most probably streptococci, thus demonstrating that the syndrome probably has a heterogeneous, toxin-related etiology.