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Biomedical subjects

A Nixon

Publications and source records attributed to A Nixon.

At least 19 recordsLinked to original sources
PubMed2004

Evaluation of decision criteria for detection of spinal cord compression based on cervical myelography in horses: 38 cases (1981-2001).

REASONS FOR PERFORMING STUDY: Different criteria have been described based on height reduction of the total myelographic contrast column and components of it as tests for compression of the spinal cord due to cervical stenotic myelopathy (CSM). Fifty percent height reduction of the dorsal myelographic column (DMC), <2 mm empiric height of the DMC and a 40% reduction of the ratio of stenosis calculated based on the height reduction of the entire dural diameter (DD) have been described as decision criteria for considering the test result positive. The reasons for selecting these decision criteria or their accuracies have rarely been reported. OBJECTIVES: To evaluate the accuracy of diagnostic criteria based on reduced height of the total myelographic column and components of it for diagnosing extradural spinal cord compression using different decision criteria, and make recommendations for consistent myelographic interpretation in horses suspected of having CSM. METHODS: Four measurements were obtained by 2 readers in a retrospective sample population of 38 horses in which both cervical myelography and histopathological examination of the cervical spinal cord were performed. The prevalence of CSM in the sample was 50%. At intervertebral sites, the minimum heights of the DD and DMC were measured. At intravertebral sites, the maximum heights of the entire DD and DMC were obtained. Percent height reductions of the DMC and DD were determined as the ratio of minimum intervertebral height to maximum intravertebral height within the next cranial vertebra. Histological examination was used as the gold standard for determining the actual site of spinal cord compression. Sensitivity and specificity for the diagnostic criteria were estimated at each site in neutral and flexed neck positions using several different decision criteria. CONCLUSIONS: At C6-C7, in neutral or flexed neck position and using 20% reduction of DD, the test was highly sensitive and specific for CSM. At other sites, reduced height of the myelographic column generally was not accurate for diagnosing extradural spinal cord compression. Using 20% reduction of DD in neutral position at the mid-cervical sites, the test had only low sensitivity and high specificity. Flexion of the neck appeared to increase detection of spinal cord compression in the mid-cervical region, but also substantially increased the frequency of false-positive diagnoses. POTENTIAL RELEVANCE: By using the reported sensitivity and specificity estimates, readers may decide on a decision criterion for diagnosis of extradural spinal cord compression due to CSM. However, in planning a surgical correction, it is difficult to define a decision criterion that combines acceptable sensitivity and specificity, especially at the mid-cervical sites.

Animals↗
PubMed2000

Effect of radiotherapy after breast-conserving treatment in women with breast cancer and germline BRCA1/2 mutations.

PURPOSE: Recent laboratory data suggest a role for BRCA1/2 in the cellular response to DNA damage. There is a paucity of clinical data, however, examining the effect of radiotherapy (RT), which causes double-strand breaks, on breast tissue from BRCA1/2 mutation carriers. Thus the goals of this study were to compare rates of radiation-associated complications, in-breast tumor recurrence, and distant relapse in women with BRCA1/2 mutations treated with breast-conserving therapy (BCT) using RT with rates observed in sporadic disease. PATIENTS AND METHODS: Seventy-one women with a BRCA1/2 mutation and stage I or II breast cancer treated with BCT were matched 1:3 with 213 women with sporadic breast cancer. Conditional logistic regression models were used to compare matched cohorts for rates of complications and recurrence. RESULTS: Tumors from women in the genetic cohort were associated with high histologic (P =.0004) and nuclear (P =.009) grade and negative estrogen (P=.0001) and progesterone (P=.002) receptors compared with tumors from the sporadic cohort. Using Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity scoring, there were no significant differences in acute or chronic morbidity in skin, subcutaneous tissue, lung, or bone. The 5-year actuarial overall survival, relapse-free survival, and rates of tumor control in the treated breast for the patients in the genetic cohort were 86%, 78%, and 98%, respectively, compared with 91%, 80%, and 96%, respectively, for the sporadic cohort (P = not significant). CONCLUSION: There was no evidence of increased radiation sensitivity or sequelae in breast tissue heterozygous for a BRCA1/2 germline mutation compared with controls, and rates of tumor control in the breast and survival were comparable between BRCA1/2 carriers and controls at 5 years. Although additional follow-up is needed, these data may help in discussing treatment options in the management of early-stage hereditary breast cancer and should provide reassurance regarding the safety of administering RT to carriers of a germline BRCA1/2 mutation.

Adult↗
PubMed2000

Molecular structure of Escherichia coli PurT-encoded glycinamide ribonucleotide transformylase.

In Escherichia coli, the PurT-encoded glycinamide ribonucleotide transformylase, or PurT transformylase, catalyzes an alternative formylation of glycinamide ribonucleotide (GAR) in the de novo pathway for purine biosynthesis. On the basis of amino acid sequence analyses, it is known that the PurT transformylase belongs to the ATP-grasp superfamily of proteins. The common theme among members of this superfamily is a catalytic reaction mechanism that requires ATP and proceeds through an acyl phosphate intermediate. All of the enzymes belonging to the ATP-grasp superfamily are composed of three structural motifs, termed the A-, B-, and C-domains, and in each case, the ATP is wedged between the B- and C-domains. Here we describe two high-resolution X-ray crystallographic structures of PurT transformylase from E. coli: one form complexed with the nonhydrolyzable ATP analogue AMPPNP and the second with bound AMPPNP and GAR. The latter structure is of special significance because it represents the first ternary complex to be determined for a member of the ATP-grasp superfamily involved in purine biosynthesis and as such provides new information about the active site region involved in ribonucleotide binding. Specifically in PurT transformylase, the GAR substrate is anchored to the protein via Glu 82, Asp 286, Lys 355, Arg 362, and Arg 363. Key amino acid side chains involved in binding the AMPPNP to the enzyme include Arg 114, Lys 155, Glu 195, Glu 203, and Glu 267. Strikingly, the amino group of GAR that is formylated during the reaction lies at 2.8 A from one of the gamma-phosphoryl oxygens of the AMPPNP.

Adenylyl Imidodiphosphate↗
PubMed2000

The relation between the presence and extent of lobular carcinoma in situ and the risk of local recurrence for patients with infiltrating carcinoma of the breast treated with conservative surgery and radiation therapy.

BACKGROUND: When found in an otherwise benign biopsy, lobular carcinoma in situ (LCIS) has been associated with an increased risk of development of a subsequent invasive breast carcinoma. However, the association between LCIS and the risk of subsequent local recurrence in patients with infiltrating carcinoma treated with conservative surgery and radiation therapy has received relatively little attention. METHODS: Between 1968 and 1986, 1625 patients with clinical Stage I-II invasive breast carcinoma were treated at the Joint Center for Radiation Therapy at Harvard Medical School with breast-conserving surgery (CS) and radiation therapy (RT) to a total dose to the primary site of > or =60 grays. Analysis was limited to 1181 patients with infiltrating ductal carcinoma, infiltrating lobular carcinoma, or infiltrating carcinoma with mixed ductal and lobular features who, on review of their histologic slides, had sufficient normal tissue adjacent to the tumor to evaluate for the presence of LCIS and also had a minimum potential follow-up time of 8 years. The median follow-up time was 161 months. RESULTS: One hundred thirty-seven patients (12%) had LCIS either within the tumor or in the macroscopically normal adjacent tissue. The 8-year crude risk of recurrence was not significantly increased for patients with LCIS associated with invasive ductal, invasive lobular, or mixed ductal and lobular carcinoma. Among the 119 patients with associated LCIS adjacent to the tumor, the 8-year rate of local recurrence was 13%, compared with 12% for the 1062 patients without associated LCIS. For the 70 patients with moderate or marked LCIS adjacent to the tumor, the 8-year rate of local recurrence was 13%. The extent of LCIS did not affect the risk of recurrence. The risks of contralateral disease and of distant failure were similarly not affected by the presence or extent of LCIS. CONCLUSIONS: Breast-conserving therapy involving limited surgery and radiation therapy is an appropriate method of treating patients with invasive breast carcinoma with or without associated LCIS. Neither the presence nor the extent of LCIS should influence management decisions regarding patients with invasive breast carcinoma. [See editorial counterpoint and reply to counterpoint on pages 978-81 and 982-3, this issue.]

Breast Neoplasms↗
PubMed2000

Quantitative three-dimensional analysis of chondrocytic kinetic responses to short-term stapling of the rat proximal tibial growth plate.

Although it has been demonstrated clinically that controlled compression across a growth plate will slow the rate of endochondral ossification and thus can be used to correct angular limb deformities, the cellular-based mechanism by which altered growth is achieved is poorly understood. This study used short-term uniaxial stapling of the rat proximal tibial growth plate as an experimental system to study chondrocytic responses in the growth plate that account quantitatively for the decreased rate of growth. Growth plates were labeled with oxytetracycline to measure bone growth, and with bromodeoxyuridine to analyze proliferative cell kinetics. Multiple indicators of chondrocytic activity, measured by stereological parameters, were analyzed using growth rate as the primary dependent variable. The unique feature of this analysis was the creation of three-dimensional reconstructions that allowed analysis of data in all directions with distance from the staple. A significant observation was that for the entire operated limb after both 3 and 6 days, all chondrocytic kinetic parameters were affected, indicating that proliferative and hypertrophic responses both act to decrease growth rate in response to stapling. This contradicted our hypothesis that proliferative and hypertrophic responses could occur independently, and that small changes in rate would be attributed primarily to the former and large changes to the latter. The data from this study also demonstrate that volume regulation during hypertrophy can be affected by a primarily mechanical perturbation. Because changes in hypertrophic cell number and volume throughout the growth plate that occur by day 3 remain similar at day 6, the initial modulation of chondrocytic volume and shape may represent the limit of the response while maintaining a growth plate capable of continued growth.

Animals↗
PubMed2000

Outcome at 8 years after breast-conserving surgery and radiation therapy for invasive breast cancer: influence of margin status and systemic therapy on local recurrence.

PURPOSE: To examine the relationship between pathologic margin status and outcome at 8 years after breast-conserving surgery and radiation therapy. PATIENTS AND METHODS: The study population comprised 533 patients with International Union Against Cancer/American Joint Committee on Cancer clinical stage I or II breast cancer who had assessable margins, who received at least 60 Gy to the primary tumor bed, and who had more than 8 years of potential follow-up. Each margin was scored (according to the presence of invasive or in situ disease that touched the inked surgical margin) as one of the following: negative, close, focally positive, or extensively positive. Outcome at 8 years was calculated using crude rates of first site of failure. A polychotomous logistic regression analysis was performed. Median follow-up time was 127 months. RESULTS: At 8 years, patients with close margins and those with negative margins both had a rate of local recurrence (LR) of 7%. Patients with extensively positive margins had an LR rate of 27%, whereas patients with focally positive margins had an intermediate rate of LR of 14%. In the polychotomous logistic regression model, margin status and the use of systemic therapy were the only two variables that had significant effects on the risk ratio of LR to remaining alive and free of disease. Among the 45 patients with focally positive margins who received systemic therapy, the crude LR rate was 7% at 8 years (95% confidence interval, 1% to 20%). CONCLUSION: Pathologic margin status and the use of adjuvant systemic therapy are the most important factors associated with LR among patients treated with breast-conserving surgery and radiation therapy.

Adult↗
PubMed1999

Phase II trial of docetaxel, cisplatin, fluorouracil, and leucovorin as induction for squamous cell carcinoma of the head and neck.

PURPOSE: To evaluate the toxicity and efficacy of a 4-day regimen of docetaxel, cisplatin, fluorouracil, and leucovorin (TPFL4) in patients with locoregionally advanced squamous cell carcinoma of the head and neck (SCCHN). PATIENTS AND METHODS: Thirty previously untreated patients with stage III or IV SCCHN and Eastern Cooperative Oncology Group functional status of 2 or less were treated with TPFL4. Postchemotherapy support included prophylactic growth factors and antibiotics. Patients who achieved a complete response (CR) or partial response (PR) to three cycles of TPFL4 received definitive twice-daily radiation therapy. The primary end points were toxicity and response to TPFL4. RESULTS: Eighty-five cycles were administered to 30 patients. The major acute toxicities to TPFL4 were mucositis and nausea. One patient died of neutropenic sepsis during therapy. Additional major toxicities were neutropenia, anorexia, nephropathy, neuropathy, and diarrhea. Fourteen percent of all cycles were associated with hospitalization for toxicity. The overall clinical response rate to TPFL4 was 93%, with 63% CRs and 30% PRs. Primary tumor site clinical and pathologic response rates were 93% and 68%, respectively. CONCLUSION: TPFL4 has an acceptable toxicity profile in good-performance-status patients. Modification of the 5-day TPFL regimen (TPFL5: shorter chemotherapy infusion time, earlier intervention with growth factors and antibiotics) led to fewer episodes of febrile neutropenia and hospitalization. Response rates to TPFL justify further evaluation of combinations of these agents in the context of formal clinical trials.

Adult↗
PubMed1998

Correlation of tumor size and axillary lymph node involvement with prognosis in patients with T1 breast carcinoma.

BACKGROUND: The prognosis of patients with T1 breast carcinoma remains controversial. Some studies have shown a low risk of lymph node metastasis and distant failure whereas others have not, possibly due to differences in the definition of tumor size. In this study, the authors assessed the relation between macroscopic tumor size, microscopic invasive tumor size, axillary lymph node involvement, and prognosis in a group of patients with clinically lymph node negative disease. METHODS: Between 1968 and 1986, 1865 women with American Joint Committee on Cancer clinical Stage I or II infiltrating carcinoma of the breast were treated at the Joint Center for Radiation Therapy with conservative surgery and radiation therapy. The study population was limited to 118 patients with clinically negative axillary lymph nodes for whom the macroscopic pathologic tumor size was identified unambiguously as being < or = 2.0 cm, who underwent an axillary lymph node dissection with at least 6 lymph nodes sampled, and for whom the microscopic size of the invasive component could be determined. The median follow-up time for surviving patients was 134 months (range, 90-208 months). No patients with pathologically negative axillary lymph nodes received systemic therapy. RESULTS: Macroscopic and microscopic tumor sizes differed by > 5 mm in 17 patients (14%), by 3-5 mm in 24 patients (20%), and by < or = 2 mm in 77 patients (65%). The macroscopic tumor size was smaller than the microscopic size in 37 patients (31%), larger in 55 patients (47%), and equal in 26 patients (22%). Pathologic axillary lymph node involvement was present in 21% of all patients. The risk of lymph node involvement was not significantly different for those patients with tumors < or = 1 cm compared with patients with tumors > or = 1.1 cm, regardless of whether tumor size was measured by macroscopic or microscopic examination. The 10-year actuarial rate of freedom from distant recurrence (FFDR) was 91% for lymph node negative patients with macroscopic tumors measuring < or = 1.0 cm compared with 77% for patients with macroscopic tumors measuring > or = 1.1 cm (P = 0.07). When measured microscopically, the rates were 96% and 72%, respectively (P = 0.001). CONCLUSIONS: There often is a discrepancy between microscopic tumor size and macroscopic tumor size. T1 tumors have a substantial risk of axillary lymph node metastasis whether measured macroscopically or microscopically. Among those patients with pathologic lymph node negative tumors who are not treated with systemic adjuvant therapy, microscopic invasive tumor size is a better predictor of 10-year FFDR than macroscopic tumor size. There is a substantial risk of distant failure for patients with tumors whose invasive component microscopically measure > or = 1.1 cm, whereas the prognosis for patients with tumors that microscopically measured < or = 1 cm is excellent. These results suggest that the microscopic size of the invasive component of breast carcinomas < or = 2.0 cm routinely should be reported.

Adult↗
PubMed1998

Family history and treatment outcome in young women after breast-conserving surgery and radiation therapy for early-stage breast cancer.

PURPOSE: To evaluate the safety and efficacy of breast-conserving therapy for young women with a family history (FH) suggestive of inherited breast cancer susceptibility. MATERIALS AND METHODS: A total of 201 patients aged 36 or younger at diagnosis treated with breast-conserving surgery and radiation therapy (> or = 60 Gy) for early-stage breast cancer were categorized by FH. FH was considered positive in 29 patients who, at the time of diagnosis, had a mother or sister previously diagnosed with breast cancer before age 50 or ovarian cancer at any age. Clinical, pathologic, and demographic variables; sites of first failure; disease-free survival; and overall survival (OS) were compared between FH-positive and -negative groups. Median follow-up time was 11 years. RESULTS: Patient and tumor features were similar between those with and without an FH. Regression analysis of sites of first failure at 5 years demonstrated a risk ratio (RR) of 5.7 for opposite breast cancer for FH-positive patients. Rates of local, regional, and distant failure and disease-free survival or OS did not differ between FH-positive and -negative patients. Age at diagnosis and Ashkenazi heritage were not significantly predictors of patterns of failure. CONCLUSION: Breast-conserving surgery combined with radiation therapy is not associated with a higher rate of local recurrence, distant failure, or second (non-breast) cancers in young women with an FH suggestive of inherited breast cancer susceptibility compared with young women without an FH. However, their increased risk of opposite breast cancer should be taken into account when considering breast conservation as a treatment option.

Adult↗
PubMed1997

Is machine energy (4-8 MV) associated with outcome for stage I-II breast cancer patients?

PURPOSE: To assess the relationship between machine energy (4-8 MV) and treatment outcome in patients treated with conservative surgery and radiation therapy. METHODS AND MATERIALS: Between 1968 and 1985, 1624 patients were treated for clinical Stage I or II invasive breast cancer. The study population was limited to 1380 patients who underwent complete gross excision and received greater than or equal to 60 Gy to the tumor bed. Of these, 1125 were treated on a 4 MV, 153 on a 6 MV, and 102 on an 8 MV linear accelerator. Patients were selected for treatment on the 8 MV machine based on chest wall separations greater than 24 cm. Of patients treated on the 8 MV, netting was used for 42% and bolus was used for 26%. The median dose with bolus was 14 Gy in seven fractions (range: 2-34.2 Gy). Patients treated on the 8 MV accelerator were older, had a higher percentage of clinical T2 tumors, a higher percentage of pathologically positive nodes, and a lower incidence of extensive intraductal component (EIC). Median follow-up times were 130, 153, and 102 months, respectively, for survivors treated on the 4, 6, and 8 MV machines. RESULTS: We analyzed the site and 5-year crude incidence of first failure by machine energy and found the pattern of first failure site (local, nodal, or distant) to be virtually identical for each energy group. Of the local failures, 12 were in the skin of the treated breast, and these failures were evenly distributed by machine energy. We performed a multivariate analysis to adjust for factors known to predict for treatment failure. When adjusted for these other variables, machine energy was not associated with an increased (or decreased) risk of recurrence (RR for 8 MV vs. 4 MV = 0.94, p = 0.7; RR for 6 MV vs. 4 MV = 1.0, p = 0.9). We also analyzed the nature and incidence of treatment complications (rib fracture, radiation pneumonitis, soft tissue necrosis, and brachial plexopathy) and found no significant differences among the three treatment groups when stratified by treatment technique (tangents only vs. three-field). There was also no significant difference in cosmetic outcome at 5 years among the three groups. CONCLUSIONS: We conclude that machine energy over the range of 4 to 8 MV does not significantly affect treatment outcome. Specifically, it was feasible to treat patients with large chest wall separations using an 8 MV machine without an increase in skin recurrences and with the improved dose homogeneity afforded by 8 MV machines as compared with those of lower energies.

Adult↗
PubMed1997

Effect of the non peptide angiotensin II antagonist, GR117289C on the vasoconstrictor actions of angiotensin II in the human forearm.

AIMS: GR117289C is a non peptide, selective angiotensin (AT1) receptor antagonist. The purpose of this study was to determine whether this agent, given orally, could attenuate the vasoconstrictor effects of angiotensin II(AII) infused locally into the forearm circulation in man. METHODS: Eight healthy male subjects were studied on four occasions in a randomized, double-blind, placebo controlled, crossover study. Five hours (approximate time of peak dynamic effect) following dosing with GR117289C (300 mg, 100 mg, 10 mg or placebo), A II was infused in incremental doses (0, 0.1, 0.4, 1.6, 6.2, 25 and 100 pmol min-1) into the left brachial artery, each for 10 min. Forearm blood flow was measured using venous occlusion plethysmography. RESULTS: GR117289C inhibits the vasoconstrictor effects of A II in a dose dependent manner. The active treatment: placebo ratios of forearm blood flow in the infused arm during the highest dose of AII (100 pmol min-1) were: GR117289C 10 mg, 1.12 (95% C.I. 0.81-1.55; P = 0.478), 100 mg, 1.43 (95% C.I. 1.01-2.01; P = 0.042) and 300 mg, 1.62 (95% C.I. 1.17-2.24; P = 0.006). There was no significant difference in blood pressure between each of the treatment groups and placebo. CONCLUSIONS: GR117289C is a pharmacologically active, oral A II antagonist in healthy men.

Administration, Oral↗
PubMed1996

Schistosomiasis: a review of cases in Wellington 1993-4.

AIM: To review those cases of Schistosoma haematobium presenting in Wellington during 1993 and 1994. METHOD: All patients receiving praziquantel during 1993 and 1994 were traced through local pharmacy records. Their clinical records were reviewed and they were contacted by phone to ensure a complete set of information was obtained. This included timing of possible exposure to the parasite, symptoms, investigations and response to treatment. RESULTS: Nine patients were identified who had been treated with praziquantel during this period. The records of six patients were available for review, all of whom had recently travelled to Africa and had swum in water contaminated with the parasite. Four had presented to medical practitioners with irritative voiding symptoms and scant intermittent haematuria. One presented with haematospermia and one after becoming aware that a friend had contracted schistosomiasis. All were treated with a single dose of praziquantel. CONCLUSIONS: This paper has demonstrated an increased number of cases of Schistosoma haematobium being identified in Wellington. The prevalence of this condition is low, but has been seen to increase recently and relates to the increasing numbers of New Zealanders touring Africa. Patients present with relatively mild, nonspecific symptoms which require a high index of suspicion to ensure that appropriate investigations are ordered. The currently available treatment is efficacious and relatively well tolerated.

Adult↗
PubMed1992

Adjuvanticity of stearyl tyrosine on the antibody response to peptide 503-535 from HIV gp160.

In this present report we compare the humoral immune response induced by immunization with an HIV-1 gp160 peptide corresponding to amino acid sequence 503-535 complexed with different adjuvants. Specifically, the antipeptide, anti-HIV-1 gp160 and neutralizing antibody responses were measured in groups of mice and baboons that received peptide 503-535 conjugated to a carrier protein in either saline, alum, or stearyl tyrosine. The highest antibody responses were induced when mice and baboons were immunized with peptide adsorbed on stearyl tyrosine. These data indicate that stearyl tyrosine represents a potent candidate as a nontoxic adjuvant not only for subunit viral vaccines, but also for HIV peptides.

Adjuvants, Immunologic↗
PubMed1988

Simultaneous quantification of five odorous steroids (16-androstenes) in the axillary hair of men.

Five 16-androstenes have been simultaneously quantified in extracts of the axillary hair of men (age range 18-40 years) using combined capillary gas chromatography-mass spectrometry, with specific ion monitoring. Quantities found (pmol/mg.hair, with approximate 24-h totals in parentheses) were: 5 alpha-androst-16-en-3-one, 0-15 (0-433); 4, 16-androstadien-3-one, 0-143 (0-4103); 5,16-androstadien-3 beta-ol, 0-3.5 (0-728); 5 alpha-androst-16-en-3 alpha-ol, 0-17 (0-1752) and 5 alpha-androst-16-en-3 beta-ol, 0-4 (0-416). There were no significant relationships with age of the subjects for any of the steroids measured but significant relationships were found between the amounts of the two ketones and between 5 alpha-androst-16-en-3 alpha- and 3 beta-ols. These findings may indicate the existence of a pathway of metabolism in axillary bacteria in which 4,16-androstadien-3-one is reduced to 5 alpha-androst-16-en-3-one and thence to the 3 alpha- and 3 beta-alcohols. The data are discussed in the context of axillary odour because of the low olfactory thresholds of several of the 16-androstenes measured and because of the relatively large quantities found in some subjects.

Adult↗
PubMed1986

Testosterone metabolism by isolated human axillary Corynebacterium spp.: a gas-chromatographic mass-spectrometric study.

Transformations of [4-14C]testosterone have been studied in Corynebacterium spp. isolated from the axillae of men. Metabolites have been separated by TLC and capillary gas chromatography and have been identified by gas chromatography-mass spectrometry (GC-MS). The introduction of a clean-up step using Florisil columns, prior to TLC, removed Tween-80 which co-extracted from the medium with the metabolites. This procedure greatly improved TLC resolution. Testosterone was converted enzymically to 5 alpha- and 5 beta-DHT, identification being assisted by the inclusion of [3,4-13C]testosterone in some incubations. Other metabolites formed enzymically were 4-androstene-3,17-dione, 5 beta-androstane-3,17-dione, 3 beta-hydroxy-5 beta-androstan-17-one and 5 beta-androstane-3 alpha .17 alpha-diol. Some spontaneous breakdown of [14C]testosterone occurred giving rise to 5 alpha (beta)-DHT, androstanediol and a monohydroxy-diketo-androstene, the latter being reduced enzymically to 2 monohydroxy-diketo-androstanes. Under the conditions used, no clear evidence has been obtained for the formation of 5 alpha-androst-16-en-3-one, an odorous steroid that occurs in the axillae of men; the possible reasons why we were unable to prove the biosynthesis of this compound are discussed.

Autoradiography↗
PubMed1979

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History, 20th Century↗