Carcinogen-DNA adduct formation in the lungs and livers of preweanling CD-1 male mice following administration of [3H]-6-nitrochrysene, [3H]-6-aminochrysene, and [3H]-1,6-dinitropyrene.

6-Nitrochrysene (NC) and 6-aminochrysene (AC) have been shown to be potent lung and liver carcinogens when administered in multiple i.p. doses to preweanling mice. 1,6-Dinitropyrene has been shown to be a strong hepatocarcinogen but a weak lung carcinogen in this same bioassay. We have examined carcinogen-DNA adduct profiles in the target tissues of preweanling male CD-1 mice following administration of single or multiple doses of these compounds. Depending on the tissue and the dosing schedule, the total level of DNA modification in animals dosed with [3H]NC was 2- to 9-fold higher than in animals dosed with [3H]AC. Regardless of the dosing schedule, DNA isolated from the lungs and livers of both [3H]NC- and [3H]AC-treated preweanling male mice contained a single major and chromatographically identical adduct. This major adduct, which accounted for as much as 90% of the total carcinogen-DNA adducts in enzymatic hydrolysates from treated animals, was chromatographically distinct from the major C8-purine-substituted adducts formed from the reaction of N-hydroxy-AC with calf thymus DNA. In contrast to the results obtained with NC and AC, the major carcinogen-DNA adduct formed in the livers of mice treated with [3H]-1,6-dinitropyrene was found to cochromatograph with 1-N-(deoxyguanosin-8-yl)amino-6-nitropyrene, a product derived from N-hydroxy-1-amino-6-nitropyrene. Since NC and its nitro-reduced derivative, AC, yielded an identical carcinogen-DNA adduct in vivo and this adduct was not derived from N-hydroxy-AC, we conclude that the metabolic activation of NC in the neonatal mouse must involve some previously undescribed combination of ring-oxidation and nitro-reduction pathways. This activation pathway could be an important factor in determining the potency of NC and AC as carcinogens in this bioassay system.

Metabolic activation of 6-nitrochrysene in explants of human bronchus and in isolated rat hepatocytes.

It has previously been shown that 6-nitrochrysene can be activated to electrophilic species capable of reacting with DNA through metabolic pathways that form N-hydroxy-6-aminochrysene or trans-1,2-dihydroxy-1,2-dihydro-6-aminochrysene as critical intermediates. Since the lung is a known target tissue for the carcinogenic action of polycyclic nitroaromatic hydrocarbons, we investigated the metabolism and DNA binding of [3H]6-nitrochrysene in 11 specimens of human bronchus. Analysis of medium from [3H]6-nitrochrysene-treated explants indicated the presence of trans-9,10-dihydroxy-9,10-dihydro-6-nitrochrysene (0.04-330 pmol/mg epithelial DNA), trans-1,2-dihydroxy-1,2-dihydro-6-nitrochrysene (12-1700 pmol/mg epithelial DNA), 6-aminochrysene (1.6-2200 pmol/mg epithelial DNA), and trans-1,2-dihydroxy-1,2-dihydro-6-aminochyrsene (3.6-610 pmol/mg epithelial DNA). Both the levels and the relative proportions of these metabolites varied widely in explants from different individuals. The amount of DNA recovered and the level of DNA modification were sufficient for adduct analysis in eight of the 11 cases for which metabolite data were obtained. Five additional bronchial specimens for which metabolite data were not obtained were also analyzed for carcinogen-DNA adducts. The levels of binding varied from 0.06 to 30.5 pmol [3H]6-nitrochrysene bound/mg DNA (two adducts per 10(8) nucleotides-10 adducts per 10(6) nucleotides). HPLC analyses of enzymatic hydrolysates of the explant DNA indicated that 11 of 13 cases contained adducts with retention times identical to those of adducts derived from trans-1,2-dihydroxy-1,2-dihydro-6-aminochrysene or N-hydroxy-6-aminochrysene. The adduct derived from trans-1,2-dihydroxy-1,2-dihydro-6-aminochrysene was the major adduct detected in eight of 13 cases. The reasons for the variation in metabolism and adduct formation observed in [3H]6-nitrochrysene-treated explants of bronchus from different donors are not known but may reflect differences in the activities of enzymes responsible for the metabolism of this compound. The influence of induction of drug metabolizing enzymes on the activation pathway of 6-nitrochrysene in an intact cell system was tested using rat hepatocytes. 6-Nitrochrysene was incubated with freshly isolated hepatocytes from rats that were either untreated or pretreated with phenobarbital, 3-methylcholanthrene or Aroclor 1254. Although the levels of adducts were similar in all cases, the pattern of DNA adducts formed in these hepatocytes was dependent on the nature of the pretreatment of the rats. As previously reported, hepatocytes from untreated rats contained adducts derived from N-hydroxy-6-aminochrysene.(ABSTRACT TRUNCATED AT 400 WORDS)

Purification, and phosphorylation in vivo and in vitro, of phosphoenolpyruvate carboxykinase from cucumber cotyledons.

Phosphoenolpyruvate carboxykinase (PEPCK) with a subunit molecular mass of 74 kDa has been purified 450-fold to homogeneity from the cotyledons of cucumber (Cucumis sativus L.). This is the first purification of the native form of the enzyme from any plant tissue. Incubation of the purified enzyme with [gamma-32P]ATP and either phosphoenolpyruvate-carboxylase kinase or mammalian cAMP-dependent protein kinase led to labelling of the enzyme in a part of the molecule separate from the active site. This was reversed by incubation with protein phosphatase 2A. Cotyledons of cucumber seedlings were also supplied with 32Pi. Homogenates of such cotyledons contained a heavily labelled polypeptide which was confirmed as PEPCK by immunoprecipitation. Labelling of PEPCK by 32Pi in darkened cotyledons was reversed by illumination.

The role of intestinal microflora in the metabolic activation of 6-nitrochrysene to DNA-binding derivatives in mice.

6-Nitrochrysene has previously been shown to be a potent lung and liver carcinogen following i.p. administration to newborn mice and to be metabolically activated to DNA-binding derivatives by nitro-reduction or a combination of nitro-reduction and ring oxidation. In this study, we have examined fecal metabolites and DNA-carcinogen adducts in 5-week-old conventional and germfree Balb/c mice treated with [3H]6-nitrochrysene in order to determine if the metabolic activation pathway(s) for this compound in these mice differs from that observed in preweanling mice. We further evaluated the role of the intestinal microflora on the metabolism and generation of DNA-reactive metabolites in this system. The amount of 6-aminochrysene excreted in the feces of germfree mice within 48 h after treatment with a single i.p. dose of [3H]6-nitrochrysene (0.03 mumol/5 microliters/g body wt) was approximately 25% of that excreted in identically treated conventional mice. However, the levels of carcinogen-DNA adducts in the lungs and livers of conventional and germfree Balb/c mice were similar at the 24 and 48 h time points examined. HPLC analysis of hydrolysates of liver and lung DNA indicated that adducts derived from both N-hydroxy-6-aminochrysene and trans-1,2-dihydroxy-1,2-dihydro-6-aminochrysene metabolites were formed in the liver whereas only the latter adduct was detected in the lung. This contrasts with previous findings in preweanling mice where the adduct derived from the trans-1,2-dihydroxy-1,2-dihydro-6-aminochrysene metabolite was the single major adduct detected in both liver and lung DNA. The proportion of adducts derived from N-hydroxy-6-aminochrysene was significantly greater in the liver DNA of germfree mice than in the liver DNA of conventional mice.

UGP--a tumor marker of gynecologic and breast malignancies? Specificity and sensitivity in pretherapeutic patients and the influence of hormonal substitution on the expression of UGP.

Urinary gonadotropin peptide (UGP) is a 10,300 Dalton peptide which is present in the urine of pregnant women, those with trophoblast disease and those with, certain nontrophoblastic malignancies. We examined the efficiency of UGP measurement at differentiating benign from malignant gynecologic and breast diseases. UGP was measured in 1355 spot urine samples from 841 patients (343 samples from 323 healthy women and women with benign gynecologic and breast diseases, 1012 samples from 518 women with gynecologic malignant diseases or breast cancer). Using a cutoff of > 3 fmol UGP/mg urinary creatinine the specificity was 97%. The sensitivity of UGP was calculated from pretherapeutically collected samples (n = 210). The sensitivity of the test for all malignancies was 26% (ovarian malignancy (n = 27) 52%, endometrial cancer (n = 25) 32%, cervical cancer (n = 49) 29%, breast cancer (n = 72) 19%, vulvar cancer and vaginal cancer (n = 12) 17% and for carcinoma in situ of the breast or the cervix (n = 20) 0%). We also found significantly higher UGP values in postmenopausal women than in premenopausal women. Hormonal substitution significantly lowered the UGP values.

Nodular disease during pregnancy.

The incidence of autoimmune disease of the thyroid approaches 10% in women. This autoimmune state, which predisposes to the development of thyroid neoplasia, especially in patients with subclinical hypothyroidism, combined with tumor growth and immunologic factors that occur in the pregnant state, account for the significant incidence of nodular thyroid disease in pregnancy. Thyroid carcinoma of follicular cell origin in a young woman can generally be expected to pursue a slow course with ample time for preoperative preparation and operative treatment. However, the pregnant state should be considered an exception and thyroid nodular disease with suspicious aspiration cytologic features should be managed with a certain degree of urgency. In an excellent article on the subject of pregnancy as a predisposing factor in thyroid neoplasia, Rosen and Walfish present a series of 30 patients with thyroid neoplasia arising during pregnancy. The incidence of thyroid carcinoma was 43% and the incidence of adenoma 37%, for an 80% overall incidence of neoplasia. Furthermore, during the course of the pregnancy, 20% of the patients showed marked increase in nodular growth, including a 26-year-old primiparous woman who developed a small nodule in the first trimester which proved to be cellular on needle aspiration biopsy. In spite of thyroid hormone treatment, the nodule grew markedly in the last trimester. At postpartum operation, the patient was found to have a papillary carcinoma with extensive unilateral neck and mediastinal node disease, which was clinically occult. These authors stress the importance of the operative treatment of thyroid neoplasia of pregnancy, either in the second trimester or immediately after delivery. We agree.

Laser-assisted uvulopalatoplasty: postoperative complications.

Laser-assisted uvulopalatoplasty (LAUP) has become a widely used procedure for the treatment of snoring and mild sleep apnea in the United States. Between July 1993 and December 1994, the authors of this study prospectively evaluated 541 consecutive patients referred to their hospital for possible LAUP to treat loud disruptive snoring. Of the 541 patients, 275 patients had a total of 754 LAUP procedures. There were 26 complications (3.45%). These complications included postoperative hemorrhage in 16 patients (2.12%), local infection in 4 patients (0.53%), temporary palatal incompetence in 4 patients (0.53% , and temporary loss of taste in 2 patients (0.27%). None of the 16 patients with postoperative hemorrhage required a blood transfusion. Only 10 patients (1.3%) had hemorrhage that required medical attention; in the other patients, the bleeding stopped spontaneously. There were no cases of hypernasal speech, permanent palatal incompetence, nasopharyngeal stenosis, airway compromise, or death.

Early polysomnographic findings and long-term subjective results in sleep apnea patients treated with laser-assisted uvulopalatoplasty.

OBJECTIVES/HYPOTHESIS: To examine the long-term results of laser-assisted uvulopalatoplasty (LAUP) for the treatment of patients with obstructive sleep apnea syndrome (OSAS). STUDY DESIGN: One hundred eighty-two OSAS patients treated with LAUP were followed for an average of 4 years. Of these patients, 131 have completed treatment. Complete polysomnographic data are available on 48 patients. Five patients were eliminated owing to nasal surgery performed during the period between the preoperative and postoperative sleep studies, thus 43 patients were included who had only LAUP treatment. Another three patients were eliminated because their postoperative polysomnograms were performed less than 6 weeks after the last procedure. Complete long-term subjective data are available on 31 patients. METHODS: Between July 1993 and July 1998, 1038 patients were evaluated for LAUP treatment for snoring and OSAS. Of the 1038 patients, 409 were treated with LAUP and the remaining 629 were treated with other surgical procedures, devices, or behavior modification. The 40 patients who underwent only LAUP treatment for OSAS and have complete polysomnographic data are the focus of this study. RESULTS: The significant objective polysomnographic findings include a decrease in the respiratory disturbance index (RDI) from 25.0 +/- 2.8 to 15.3 +/- 2.9 (P = < .0001), and a decrease in the apnea index (AI) from 14.6 +/- 2.6 to 9.0 +/- 2.4 (P = .00248). In addition, the percentage of time spent in rapid eye movement (REM) sleep significantly increased after LAUP, from 13.3% +/- 1.0 to 17.6% +/- 1.4 (P = .0149). The long-term subjective results indicate that the presenting complaints were improved after LAUP in 74.9% +/- 4.1 with a mean follow-up of 4.04 years +/- 72 days (median, 4.63 y). CONCLUSIONS: LAUP remains a safe and effective treatment for carefully selected patients suffering from OSAS. Five years after LAUP was introduced in the United States, objective polysomnographic data demonstrate reduction in the RDI and increased time spent in REM sleep after treatment. In addition, the long-term subjective results show that the presenting symptoms were no longer present in 75% of patients treated with LAUP.

Laser-assisted uvulopalatoplasty for the treatment of mild, moderate, and severe obstructive sleep apnea.

OBJECTIVES/HYPOTHESIS: Until recently, laser-assisted uvulopalatoplasty (LAUP) has been used to treat only snoring and mild cases of obstructive sleep apnea (OSA). The purpose of this study was to evaluate the efficacy and safety of LAUP in patients with mild, moderate, and severe OSA. STUDY DESIGN: A prospective study of 38 patients who completed LAUP for the treatment of OSA who were evaluated based on the severity level of their preoperative apnea. MATERIALS AND METHODS: Between July 1993 and December 1995, 96 patients with a diagnosis of OSA based on polysomnography underwent staged outpatient LAUP treatment. Thirty-eight patients completed treatment and obtained postoperative polysomnography. Postoperative complications and polysomnographic findings were reviewed. RESULTS: Fifteen patients had a diagnosis of mild apnea, 12 had moderate apnea, and 11 had severe apnea based on preoperative polysomnography. The surgical response rates, defined as greater than or equal to 50% reduction in the postoperative respiratory disturbance index (RDI) and a postoperative RDI of less than 20, were 46.7% in the mild apneics, 41.7% in the moderate apneics, and 45.5% in the severe apneics. Postoperative complications in this series included minor bleeding, oral candidiasis, and temporary velopharyngeal insufficiency. There were no serious complications. CONCLUSIONS: In the carefully selected and prepared patient with mild, moderate, or severe OSA, LAUP should be considered a surgical option for the treatment of this disorder. LAUP remains a cost-effective and safe alternative to uvulopalatopharyngoplasty.

Preoperative differences between male and female patients with sleep apnea.

OBJECTIVES/HYPOTHESIS: To evaluate the differences between female and male patients with obstructive sleep apnea syndrome (OSAS) in the preoperative period. STUDY DESIGN: Nonrandomized cross-sectional study. METHODS: An analysis of 686 patients (111 women and 575 men) with OSAS was completed. Multivariate modeling techniques were employed to correlate gender with the preoperative respiratory disturbance index (RDI), apnea index (AI), hypopnea index (HI), body mass index (BMI), age, and initial symptoms. RESULTS: At presentation, the male patients were significantly younger and had a lower BMI and a higher RDI and AI than the female patients. For the entire OSAS population studied, the RDI increased as the BMI increased (correlation coefficient [r] = 0.35, P = <.001). For the female patients there was a weaker correlation (r = 0.21, P =.034), and in male patients there was a stronger correlation (r = 0.40, P <.001). For the entire population there was a negative correlation between age and RDI (r = -0.15, P <.001). In female patients there was a nonsignificant correlation (r = -0.09, P =.35), and in male patients the correlation was significant (r = -0.16, P <.001). There was no difference in the reporting of the number of symptoms based on gender (P =.355). Female patients noted headaches on awakening more commonly than male patients (P =.001), and male patients noted snoring (P =.014) and stopping breathing during sleep (P =.001) more often than female patients. CONCLUSIONS: The analysis demonstrated that within a surgical population sample, gender differences exist. The findings of this series were as follows: 1) Apnea severity in women was less weight-dependent than in men; (2) in men there was a significant negative correlation between age and apnea severity; and (3) female and male patients reported the same number of signs or symptoms on presentation, although certain signs and symptoms were more commonly reported based on gender. Current clinical evaluation practices must take into account this gender disparity.

Uvulopalatopharyngoplasty versus laser-assisted uvulopalatoplasty for the treatment of obstructive sleep apnea.

Uvulopalatopharyngoplasty (UPPP) was the first surgical procedure specifically designed to address the palatal abnormalities seen in many patients with obstructive sleep apnea syndrome (OSAS). For adult apneic patients, UPPP remains the most commonly performed operation. Beginning in 1993, laser-assisted uvulopalatoplasty (LAUP) was introduced for the treatment of snoring and sleep apnea. LAUP differs from UPPP because it is performed in the office using only local anesthesia, thus being very cost-effective. Seventy-nine patients with OSAS underwent surgical treatment: 38 treated with LAUP and 41 with UPPP. The overall surgical response rate, defined as a >50% reduction in the postoperative respiratory disturbance index (RDI), was achieved in 21 (51.2%) of UPPP-treated and 18 (47.4%) of LAUP-treated patients. The RDI decreased from 30.3 +/- 3.7 to 22.2 +/- 4.4 events/h in the LAUP patients and from 52.1 +/- 5.0 to 25.5 +/- 2.7 events/h in the UPPP patients. The lowest oxyhemoglobin saturation (LS(aO2)) increased from 72.8 +/- 2.1 to 80.9 +/- 1.3% in the UPPP patients; there was no change in the LAUP patients. Postoperative complications in this series included minor bleeding, oral candidiasis, and temporary velopalatal insufficiency in both groups. In the carefully selected OSAS patient, LAUP should be considered a surgical alternative to UPPP. LAUP may actually be preferable to UPPP in certain cases because LAUP is cost-effective, does not require a general anesthetic or hospitalization, has very few associated complications, and time lost at work is minimal.

Objective assessment of snoring before and after laser-assisted uvulopalatoplasty.

Laser-assisted uvulopalatoplasty (LAUP) is an outpatient staged surgical procedure for the treatment of snoring. Each patient undergoes a series of procedures with the end point being patient and bed partner satisfaction in most cases. The purpose of this study was to objectively evaluate the frequency, pattern, and volume of snoring in patients prior to and following each LAUP procedure. A sonographic device, SNAP, which records oronasal respiration, was used to assess patients at home. A digital analysis of the frequency, pattern, and volume was then performed. Twenty-seven patients have been completely evaluated with this recording device. The findings demonstrate that the LAUP procedure alters the snoring sound. The maximum, average, and velum-like respiratory noise loudness all showed a statistically significant decrease when comparing the preoperative snoring to the final recording after treatment was completed. In addition, the fundamental frequency of the snoring increased significantly after each LAUP procedure. No change was seen in the snoring index following treatment. These objective results correlated well with the subjective responses of the patients and their bed partners. These findings are consistent with the hypothesis that the LAUP procedure alters snoring in a favorable manner by both objective data and subjective accounts.

Hyperparathyroidism induced by hypothyroidism.

The coexistence of hyperparathyroidism and thyroid tumors and/or chronic thyroiditis has raised the possibility of an etiologic relationship. The present study was designed to test the hypothesis that the chronic elevation of thyroid-stimulating hormone (TSH) is related to the development of hyperparathyroidism. Three groups of 24 rats each were treated for 12 weeks as follows: group 1 received propylthiouracil (PTU) in their deionized water; group 2 received PTU and thyroid hormone to suppress TSH and to serve as a control group for possible direct effects of PTU; and group 3 was not treated at all and served as another control group. At 12 weeks, 95% of group 1 rats (PTU only) showed hyperplasia of the parathyroids with a 30% mean increase in circulating parathormone.

Laser-assisted uvulopalatoplasty for snoring and obstructive sleep apnea: results in 170 patients.

Laser-assisted uvulopalatoplasty (LAUP) is a procedure for the treatment of snoring and, possibly, sleep apnea. Between July 1993 and December 1994, the authors prospectively evaluated 541 consecutive patients referred to their teaching hospital for possible LAUP to treat loud, disruptive snoring. Of these patients, 274 (51%) had one or more LAUP treatments. As of January 1995, LAUP treatment courses were completed in 170 patients. In this paper, the authors report preliminary results on the use of LAUP in these patients. Among the 170 patients, 105 (62%) had a diagnosis of snoring and 65 (38%) obstructive sleep apnea syndrome (OSAS) based on preoperative polysomnography. LAUP treatment in the snoring only patients resulted in complete or nearly complete elimination of snoring in 63 patients (60%), partial improvement of snoring in 30 patients (29%), and no improvement in 11 patients (10%). Of the 65 OSAS patients treated with LAUP, postoperative polysomnograms were obtained in 33 patients (51%). Surgical success was achieved in 16 (48%) of the 33 patients. However, 7 patients (21%) had repeat polysomnograms that were worse than their preoperative polysomnograms, and 5 patients (15%) had no significant change. The results of this study suggest that LAUP may be a viable surgical option for patients with snoring and mild sleep apnea.

Identifying obstructive sleep apnea in patients presenting for laser-assisted uvulopalatoplasty.

The authors report on a series of 850 patients with snoring who were evaluated for laser-assisted uvulopalatoplasty (LAUP). Stepwise multivariate linear regression was employed to correlate patient symptoms and characteristics to the respiratory disturbance index (RDI). Body mass index, falling asleep while driving, snoring every night, and stopping breathing during sleep were found to correlate strongly with an increasing RDI (variance of 25%). Logistic multivariate linear regression analysis was used to predict the outcome of apnea (RDI>10). This model selected all of the above variables, as well as age, male sex, and the total number of symptoms, as being strong predictors of apnea. A receiver operating characteristic curve was used to describe the ability of this model to predict apnea. The authors conclude that otolaryngologists play an important role in the evaluation of OSAS, especially when a snoring patient may undergo LAUP, and they present an algorithm for the evaluation of such a patient. The authors believe that the clinical assessment, including a thorough history and a complete physical examination, remains extremely important in this evaluation. At present, the authors strongly recommend referral for a PSG if there is any suspicion of OSAS.

Guidelines for the use of radio-iodine, thyroid hormone, and treatment of metastatic disease in patients with differentiated thyroid cancer.

The treatment of metastatic differentiated thyroid carcinoma is currently at a crossroad. The stunning effect of imaging doses of RAI on subsequent treatment doses is being recognized. Alternatives to RAI imaging for diagnostic purposes are being tested; these include ultrasonography for local and cervical nodal remnants/recurrences, Sestamibi and other isotope scanning that do not require the discontinuation of TSH suppression, and the measurement of circulating thyroglobulin that is rapidly becoming the cornerstone of the detection and the treatment follow-up of metastatic carcinoma.

Parathyroid autotransplantation in patients undergoing a total thyroidectomy: a review of 261 patients.

Parathyroid autotransplantation was first described in 1907 by Halsted. However, this simple and effective method of preserving parathyroid function has been used with increasing frequency only during the past 25 years. Beginning in the late 1960s, our group has transplanted normal parathyroid tissue into the ipsilateral sternocleidomastoid muscle whenever these glands could not be preserved in situ with adequate blood supply. In addition, if the blood supply of all four parathyroid glands appeared compromised, cryopreservation of parathyroid tissue was performed in case the autotransplanted tissue did not function after surgery. Since 1970, 393 patients underwent a total thyroidectomy. Parathyroid glands that could not be saved in situ were biopsied to confirm their identity by frozen section and then autotransplanted. Of the 393 patients who underwent a total thyroidectomy, 261 patients required transplantation of one or more glands. Among those 261 patients who underwent selective parathyroid autotransplantation, 33 (13%) required temporary calcium and vitamin D supplementation. Of these 33 patients, 2 (less than 1%) had permanent hypoparathyroidism and are receiving long-term vitamin D therapy.

The relationship between Hashimoto's thyroiditis, thyroid neoplasia, and primary hyperparathyroidism.

The relationship between Hashimoto's thyroiditis and follicular cell carcinoma of the thyroid remains controversial. Hashimoto's thyroiditis is regarded by some as a premalignant lesion for which thyroidectomy is definitely indicated. In contrast, other investigators have found no increased evidence of thyroid carcinoma in patients with this disease. As a result, the management of thyroid nodules in patients with Hashimoto's thyroiditis remains highly individualized. A program for the management of patients with chronic Hashimoto's thyroiditis with co-existing neoplasia or primary hyperparathyroidism is outlined.

Development of monoclonal antibodies to pre-haptoglobin 2 and their use in an enzyme-linked immunosorbent assay (ELISA).

Haptoglobins (HPs) are alpha 2-globulin proteins that bind free hemoglobin in plasma to prevent oxidative damage. HPs are produced as preproteins that are proteolytically cleaved in the ER into alpha and beta chains prior to forming mature, functional tetramers. Two alleles exist in humans (HP1 and HP2), therefore three genotypes are present in the population, i.e., HP1-1, HP2-1, and HP2-2. A biochemical role for nascent haptoglobin 2 (pre-haptoglobin 2 or pre-HP2) as the only known modulator of intestinal permeability has been established. In addition, elevated levels of serum pre-HP2 have been detected in multiple conditions including celiac disease and type I diabetes, which are believed to result in part through dysregulation of the intestinal barrier. In this study, we report the development of a monoclonal antibody that is specific for pre-HP2 with a binding affinity in the nanomolar range. Additional antibodies with specificities for preHP but not mature haptoglobin were also characterized. A sandwich enzyme-linked immunosorbent assay (ELISA) was established and validated. The ELISA showed high specificity for pre-HP2 even in the presence of excess pre-HP1 or mature haptoglobins, and has excellent linearity and inter- and intra-assay reproducibility with a working range from 3.1ng/mL to 200ng/mL. Testing of sera from 76 healthy patients revealed a non-Gaussian distribution of pre-HP2 levels with a mean concentration of 221.2ng/mL (95% CI: 106.5-335.9ng/mL) and a median value of 23.9ng/mL. Compared to current approaches, this ELISA offers a validated, monoclonal-based method with high sensitivity and specificity for measuring pre-HP2 in human serum.