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R I McLachlan

Publications and source records attributed to R I McLachlan.

At least 19 recordsLinked to original sources
PubMed2006

Histological evaluation of the human testis--approaches to optimizing the clinical value of the assessment: mini review.

Testicular biopsy is a crucial assessment in reproductive practice with diagnostic and prognostic importance for assisted reproductive technologies (ARTs) and risk of testicular neoplasia. Endocrine and genetic tests cannot reliably distinguish obstructive azoospermia (OA) from non-obstructive azoospermia (NOA) or predict recovery of mature spermatids by testicular sperm extraction (TESE). Currently, divergent histological reporting systems and the use of imprecise terminology seriously degrade the value of the literature on TESE recovery rates and hamper evaluation of treatments and research on genotype-phenotype relationships. The rising incidence of testis cancer and carcinoma in situ (CIS), especially in infertile populations, requires that every effort be made for its early detection. We provide a systematic approach to the histological classification of spermatogenic disorders and detection of CIS in adult patients. We evaluate a large consecutive series of bilateral biopsies from infertile men and report (i) the frequency of bilateral or discordant patterns that supports the use of bilateral biopsy for comprehensive evaluation and (ii) a high prevalence of mixed patterns, particularly within the hypospermatogenesis classification, that helps account for reported success of TESE. We propose a new diagnosis code for testicular biopsies that addresses the needs of ART clinicians and allows data storage and retrieval of value in clinical practice and research.

Azoospermia↗
PubMed2005

Sexual activity, fertility and contraceptive use in middle-aged and older men: Men in Australia, Telephone Survey (MATeS).

BACKGROUND: With limited information regarding fertility and sexual activity in the older population, men's behaviour, attitudes and concerns were explored in a representative population of middle-aged and older men using the Men in Australia, Telephone Survey (MATeS). METHODS: A stratified random national sample of 5990 men participated in a standardized computer-assisted telephone interview. Equal numbers in the age strata 40-49, 50-59, 60-69 and >or=70 years were surveyed with findings census-standardized to the national population. Broad aspects of men's health and well-being, including reproductive health, were explored. RESULTS: The majority of men were sexually active in the last 12 months (age-standardized proportion, 78.3%) with approximately 37% of men aged >or=70 years still continuing sexual activity. Overall, 12.2% of men had never fathered children, of whom most (7.7%) had chosen not to have children. Questioning on failed attempts to produce a pregnancy suggested an involuntary infertility rate of 7.6%. The age-standardized vasectomy rate was 25.1%, with 5.6% of vasectomized men having no children. Although 9.2% of vasectomized men regretted sterilization, only 1.4% had undergone vasectomy reversal. CONCLUSIONS: Continuing sexual activity, fertility and contraception needs in middle-aged and older men suggests that education and service delivery must be more appropriately directed to an ageing population.

Adult↗
PubMed2005

Time course of changes in sperm morphometry and semen variables during testosterone-induced suppression of human spermatogenesis.

BACKGROUND: Quantification of changes in semen may give insight into the testosterone (T)-induced disruption of spermatogenesis in man. METHODS: A model analogous to flushing of sperm from the genital tract after vasectomy was used to quantify the time course of semen changes in subjects participating in male contraceptive trials using 800 mg T-implant (n = 25) or 200 mg weekly intramuscular injection (IM-T; n = 33). A modified exponential decay model allowed for delayed onset and incomplete disruption to spermatogenesis. Semen variables measured weekly during a 91-day period after initial treatment were fitted to the model. RESULTS AND CONCLUSIONS: Sperm concentration, total count, motility and morphometry exhibited similar average decay rates (5 day half-life). The mean delay to onset of decline in concentration was 15 (IM-T) and 18 (T-implant) days. The significantly longer (P < 0.005) delays deduced for the commencement of fall in normal morphology (41 days), normal morphometry (40 days) and sperm viability (43 and 55 days), and the change of morphometry to smaller more compact sperm heads are consistent with sperm being progressively cleared from the genital tract rather than continued shedding of immature or abnormal sperm by the seminiferous epithelium. A significant negative relationship was found between lag time and baseline sperm concentration, consistent with longer sperm-epididymal transit times associated with lower daily production rates.

Adult↗
PubMed2005

The Y chromosome gr/gr subdeletion is associated with male infertility.

Men with Y chromosome (Yq) AZFc deletions lack all copies of the DAZ gene and have severe spermatogenic failure. A recently described gr/gr subdeletion of AZFc removes two of four copies of DAZ. To better understand the relative frequencies of AZFc and gr/gr deletions and their associated phenotypes, we analysed two large groups of infertile men. A total of 788 men from the Monash Male Infertility (MMI) database with a range of fertility disorders showed similar overall prevalences of AZFc (2.5%) and gr/gr deletions (3.4%). There was no association of gr/gr deletions with sperm density. In 234 control men of known or presumed fertility, only one gr/gr deletion was found. In a further 599 consecutive men presenting for assisted reproductive technologies, we detected 13 (2.2%) AZFc deletions and 28 (4.7%) gr/gr deletions. All AZFc deletions were seen with sperm densities <5 million/ml but again the gr/gr deletion occurred with similar frequency across all sperm density categories. These data show that gr/gr deletions are significantly associated with infertility in the Australian population (P = 0.0015) but not exclusively with reduced sperm density suggesting a complex interaction with other factors important for male fertility. Vertical transmission of gr/gr deletions from father to son by ICSI was demonstrated in four cases. Analysis of 130 ICSI-conceived sons revealed no de novo gr/gr deletions indicating that ICSI is not a risk factor. The data suggest that testing for gr/gr deletions should be considered in the routine genetic assessment of men with idiopathic infertility.

Chromosome Deletion↗
PubMed2003

Characterization of plasma inhibin forms in fertile and infertile men.

BACKGROUND: The reciprocal relationship between plasma FSH and inhibin B generally reflects the state of spermatogenesis but data in some settings indicate further complexity in their relationship. Inhibin circulates as a range of higher molecular weight (mol wt) forms of varying bioactivity such that the serum profile of inhibin forms may differ between normal men and those with varying types of spermatogenic failure. The aim of this study was to establish if the inhibin B mol wt distribution was altered in men with infertility. METHODS: The mol wt profiles of inhibin B and free alpha-subunit were determined in plasma of fertile (n = 11) and infertile (n = 17) men using a combined immunoaffinity chromatography, preparative SDS-PAGE and electro-elution procedure and fractions assayed using ELISAs for inhibin B, total inhibin (all forms containing the alpha-subunit) and free alpha-subunit. RESULTS: Inhibin B was identified as precursor (60-65 k) and mature (26-30 k) forms in plasma in similar proportions (29%) in fertile men and oligospermic men (25%), but was undetectable in azoospermic men. The free alpha-subunit detected by the pro-alphaC ELISA was identified as both the precursor and processed (pro-alphaC) forms with similar proportions in fertile (8%) and all infertile (4-14%) men. The pro-alphaC ELISA did not detect the precursor forms of inhibin B in plasma while the inhibin B ELISA detected all total inhibin forms following removal of pro-containing forms by immunoabsorption. CONCLUSIONS: (i) the proportions of precursor inhibin B and alpha-subunit forms in the circulation are unchanged in men with spermatogenic disorders indicating there is no alteration of the Sertoli cell inhibin secretory pattern; (ii) these fractionation studies indicate that pro-alphaC and inhibin B ELISAs specifically detect the free alpha-subunit and inhibin B forms present in male plasma.

Adult↗
PubMed2003

Differential regulation of rat testicular 5alpha-reductase type 1 and 2 isoforms by testosterone and FSH.

Testosterone is metabolised to the more potent androgen, dihydrotestosterone, by the 5alpha-reductase (5alphaR) enzyme. We previously showed that 5alpha-reduced androgens are important for maintaining androgen action on rat spermatogenesis when testicular testosterone concentrations are reduced. This study investigated expression and activity of the 5alphaR isoforms, type 1 (5alphaR-1) and type 2 (5alphaR-2), in the rat during hormone manipulation in order to understand the factors that regulate the testicular concentration of 5alphaR and testicular 5alpha-reduced androgen biosynthesis. Testicular 5alphaR-1 and 5alphaR-2 mRNA and enzyme activity were measured by real-time PCR and specific enzyme assays respectively. Hormone levels were first suppressed using two models of gonadotrophin suppression: testosterone and oestradiol treatment (LH/testosterone deficiency) or GnRH immunisation (LH/testosterone and FSH deficiency). Hormones were then either restored or suppressed for 6 days by a variety of hormonal treatments. 5alphaR-1 mRNA and enzyme activity increased when testosterone was suppressed, yet restoration of testosterone decreased 5alphaR-1 mRNA and enzyme activity, suggesting that testosterone negatively regulates 5alphaR-1. suppression of FSH decreased 5alphaR-1 mRNA yet FSH administration increased 5alphaR-1 mRNA, but no changes in 5alphaR-1 activity were observed within the 6 day period. In contrast to 5alphaR-1, testosterone did not affect the testicular concentration of 5alphaR-2 mRNA or activity, but there was evidence for modulation of 5alphaR-2 activity by FSH. Measurement of testicular androgens revealed that 5alphaR-1 was primarily responsible for the production of 5alpha-reduced metabolites. It is concluded that the 5alphaR isoforms in rat testis are differentially regulated by testosterone and FSH: testosterone negatively regulated 5alphaR-1 mRNA and enzyme activity but had no affect on 5alphaR-2, whereas FSH positively regulated 5alphaR-1 mRNA and appeared to regulate 5alphaR-2.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2002

Identification of specific sites of hormonal regulation in spermatogenesis in rats, monkeys, and man.

A detailed understanding of the hormonal regulation of spermatogenesis is required for the informed assessment and management of male fertility and, conversely, for the development of safe and reversible male hormonal contraception. An approach to the study of these issues is outlined based on the use of well-defined in vivo models of gonadotropin/androgen deprivation and replacement, the quantitative assessment of germ cell number using stereological techniques, and the directed study of specific steps in spermatogenesis shown to be hormone dependent. Drawing together data from rat, monkey, and human models, we identify differences between species and formulate an overview of the hormonal regulation of spermatogenesis. There is good evidence for both separate and synergistic roles for both testosterone and follicle-stimulating hormone (FSH) in achieving quantitatively normal spermatogenesis. Based on relatively selective withdrawal and replacement studies, FSH has key roles in the progression of type A to B spermatogonia and, in synergy with testosterone, in regulating germ cell viability. Testosterone is an absolute requirement for spermatogenesis. In rats, it has been shown to promote the adhesion of round spermatids to Sertoli cells, without which they are sloughed from the epithelium and spermatid elongation fails. The release of mature elongated spermatids from the testis (spermiation) is also under FSH/testosterone control in rats. Data from monkeys and men treated with steroidal contraceptives indicate that impairment of spermiation is a key to achieving azoospermia. The contribution of 5alpha-reduced androgens in the testis to the regulation of spermatogenesis is also relevant, as 5alpha-reduced androgens are maintained during gonadotropin suppression and may act to maintain low levels of germ cell development. These concepts are also discussed in the context of male hormonal contraceptive development.

Androgens↗
PubMed2001

Sensitive LH and FSH assays for monitoring low serum levels in men undergoing steroidal contraception.

BACKGROUND AND OBJECTIVES: Current immunoassays for detecting serum FSH and LH are not sufficiently sensitive to detect the markedly reduced levels in men undergoing steroidal hormonal treatment for contraceptive purposes. The purpose of this study was to increase the sensitivity of available LH and FSH immunofluorometric (Delfia) assays in order to allow a better understanding of the importance of gonadotrophin suppression in achieving the optimal suppression of sperm count. DESIGN AND PATIENTS: Assay conditions were modified by increasing serum sample volume, the inclusion of either FSH- or LH-depleted serum to reduce the resulting matrix effects and extending incubation times. The microassays were applied to serum from 10 men administered testosterone enanthate with or without depot medroxyprogesterone acetate for 12 weeks as part of a contraceptive trial. RESULTS: The assay sensitivities were increased to 0.005 IU/l for LH and 0.010 IU/l for FSH, representing a five- to six-fold increase in sensitivity compared with existing assays. In the clinical trial, serum LH levels were suppressed to near or below the level of assay detection (mean 0.014 IU/l < 0.4% of pretreatment values) while in eight of 10 men, plasma FSH levels were detectable (0.04-0.07 IU/l, 1-5% of pretreatment values). These FSH levels would not have been detected by current assays. CONCLUSIONS: The increased sensitivities of the LH and FSH assays enabled the detection of gonadotrophins that were < 0.4% of pretreatment serum levels. Using these methods, serum LH was suppressed to nondetectable or near nondetectable levels while serum FSH was highly suppressed but still detectable in the majority of men undergoing steroidal treatment for contraceptive purposes.

Contraceptive Agents, Male↗
PubMed2001

Impairment of spermatogonial development and spermiation after testosterone-induced gonadotropin suppression in adult monkeys (Macaca fascicularis).

Human male hormonal contraceptive regimens do not consistently induce azoospermia, and the basis of this variable response is unclear. This study used nine adult macaque monkeys (Macaca fascicularis) given testosterone (T) implants for 20 weeks to study changes in germ cell populations in relation to sperm output. Germ cell numbers were determined using the optical disector stereological method. Four animals achieved consistent azoospermia (azoo group), whereas five animals did not (nonazoo group). T-induced gonadotropin suppression in all animals decreased A pale (Ap) spermatogonia to 45% of baseline within 2 weeks, leading to decreased B spermatogonia (32--38%) and later germ cells (20--30%) after 14 and 20 weeks. Though the reduction in later germ cell types could be primarily attributed to the loss of spermatogonia, the data suggested that some cells were lost during the spermatocyte and spermatid phase of development. B spermatogonial number was more markedly suppressed in azoospermic animals, compared with the nonazoo group, as was the conversion ratio between Ap and B spermatogonia. Abnormal retention of elongated spermatids (failed spermiation) was also prominent in some animals after long-term T administration. We conclude that: 1) the variable suppression of sperm output is attributed to the degree of inhibition of germ cell development from type B spermatogonia onwards, and this is related to the degree of FSH suppression; and 2) inhibition of Ap and B spermatogonial development and of spermiation are the major defects caused by long-term T administration to monkeys.

Animals↗
PubMed2000

Enzyme assay for 5alpha-reductase type 2 activity in the presence of 5alpha-reductase type 1 activity in rat testis.

The relative abundance and physiological role of 5alpha-reductase (5alphaR) isoforms in rat testis, in particular 5alpha-reductase Type 2 (5alphaR2) are poorly understood. Investigation of 5alphaR2 activity using enzyme kinetic studies was hampered by the high concentrations of 5alpha-reductase Type 1 (5alphaR1) in rat testis. Therefore, an assay was developed which exploited the differences in pH optima of the two isoforms. The 5alphaR assays measured the conversion of 3[H]-testosterone to 5alpha-reduced metabolites (dihydrotestosterone+3alpha-Androstanediol) at pH 5.0 and 7.0. To compensate for the overlap of 5alphaR1 activity at pH 5.0, the amount of 5alphaR1 activity at pH 5.0 was determined by measuring recombinant rat 5alphaR1 expressed in COS-7 cells at pH 5.0 and 7.0. The amount of activity at pH 5.0 that was attributed to 5alphaR1 was determined to be 12.4+/-1.4% (mean+/-S.D., n=14). The 5alphaR2 assay was validated by determining recombinant rat 5alphaR2 activity in the presence of recombinant rat 5alphaR1 activity in COS cells. A 99.3+/-14.7% recovery of 5alphaR2 activity was obtained when comparing 5alphaR2 activity recovered versus activity added. 5alphaR1 and 5alphaR2 activities were then assayed in rat testis extracts from 30, 75 and 147 days. Both isoforms markedly declined (50-100-fold) over this age range, with 5alphaR1 as the predominant isoform. In conclusion, an enzymatic assay that detects 5alphaR2 activity in the presence of high concentrations of 5alphaR1 was developed and is applicable in the measurement of 5alphaR2 activity in rat testis.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2000

Efficacy and acceptability of testosterone implants, alone or in combination with a 5alpha-reductase inhibitor, for male hormonal contraception.

Testosterone (T) treatment suppresses serum gonadotropins and reduces sperm output sufficiently for contraceptive efficacy in approximately 70% of Caucasian men. In the remaining 30% of men, an increase in 5alpha-reductase activity may maintain testicular androgen activity, thus accounting for the failure of sperm suppression. The form of T therapy is a major consideration in the safety and acceptability of T-based contraception. As compared to T ester injections, T implants provide a more physiological serum T profile and fewer side effects, but have not yet been used in contraceptive efficacy studies. We have used T implants (800-1200 mg every 3 months) in 29 normal men for 3-16 months. T implants produced long-term suppression of sperm densities below 1 million/mL in approximately 70% of men without significant androgenic side effects. No pregnancies occurred in 214 months of exposure. In 16 men failing to suppress within 3 months of T 800 mg, no evidence of enhanced spermatogenic suppression was seen with the co-administration of the type 2 5alpha-reductase inhibitor, finasteride, for 3 months when compared to placebo. We conclude that: 1) T implants provide adequate spermatogenic suppression in approximately 70% of Caucasian men, a rate comparable to intramuscular T injections but with minimal side effects; and, 2) the inclusion of a type 2 5alpha-reductase inhibitor does not enhance spermatogenic suppression.

5-alpha Reductase Inhibitors↗
PubMed2000

The endocrine control of spermatogenesis.

The hormonal regulation of spermatogenesis involves a complex interplay within the hypothalamo-pituitary-testicular axis, which commences before birth with male sexual development and continues through puberty and into adulthood. Hypothalamic gonadotrophin-releasing hormone drives these events by inducing pituitary gonadotrophin secretion, thereby stimulating testicular androgen secretion (providing virility) and spermatogenesis (providing fertility). Evidence from both animal models and man supports a need for both follicle-stimulating hormone and testosterone in achieving full spermatogenic potential, but a species difference in their relative roles exists. Clinical endocrine disorders can arise from a deficiency of hypothalamic gonadotrophin-releasing hormone and/or pituitary gonadotrophins, which results in hypogonadotrophic hypogonadism, featuring delayed/absent puberty and infertility. Physiologically-based and effective treatment with pulsatile gonadotrophin-releasing hormone or gonadotrophins can often restore fertility. Clinical conditions can also be caused by rare genetic disorders of the gonadotrophin molecules or the receptors for androgens and gonadotrophins, which result in a range of phenotypes (from male pseudohermaphroditism through to infertility); these disorders provide a unique insight into the physiology of sexual development and spermatogenesis.

Endocrine Glands↗
PubMed2000

CAG trinucleotide repeats in the androgen receptor gene of infertile men exhibit stable inheritance in female offspring conceived after ICSI.

The androgen receptor (AR) gene is located on the X chromosome and contains a polymorphic CAG tract. CAG repeat expansions in the AR have been associated with male infertility and the neuromuscular disease, spinal bulbar muscular atrophy (SBMA). Based on Mendelian inheritance patterns, moderate CAG expansions in infertile men treated by intracytoplasmic sperm injection (ICSI) would be vertically transmitted to female offspring. Should further elongation of the repeat region occur in the male germline, it is conceivable that longer expansions could also be transmitted by ICSI and may lead to an increased incidence of male infertility and SBMA in succeeding generations. To determine the degree of stability of the paternal AR CAG tract following ICSI, we compared the CAG repeat number in the AR alleles of 92 men presenting for ICSI and their 99 ICSI-conceived daughters. CAG repeat lengths in the AR alleles were determined by fluorescent polymerase chain reaction and Genescan analysis of amplification products separated on DNA sequencing gels. In the vast majority of cases (95 out of 99), we found that the AR CAG tracts ranging in size from 15-28 repeats exhibited stable inheritance in female offspring. However, in the remaining father-daughter pairs, there was a discordance in the expected inheritance pattern with evidence for both CAG expansion (20-->24; 22-->23) and contraction (26-->18 or 22) of the paternal AR allele. The detection of a low frequency of CAG mutation in paternal AR alleles following ICSI would be consistent with gonadal mosaicism originating from meiotic DNA replication errors. These findings in a typical group of infertile men undergoing ICSI for a variety of indications tend to alleviate concerns that ICSI may promote the transmission of AR alleles with expanded CAG tracts and suggest that the risk of SBMA in second generation sons would be extremely low.

Female↗
PubMed2000

Spermiation failure is a major contributor to early spermatogenic suppression caused by hormone withdrawal in adult rats.

Spermiation is the process by which mature sperm are released from the Sertoli cell into the lumen of the seminiferous tubule. Previous studies have shown that FSH and LH/testosterone suppression causes a significant increase in the degeneration of mature elongated spermatids. The purpose of this study was to investigate the extent to which spermiation failure contributes to the overall failure of spermatogenesis during hormone suppression. We used in vivo models to selectively suppress either FSH, by passive immunization, and or testosterone, by administration of SILASTIC brand (Dow Corning) testosterone and estradiol implants to suppress LH and testicular testosterone production. Stereological quantitation of the number of step 17-18 spermatids before spermiation and the number of step 19 spermatids retained within the epithelium after spermiation showed that 2% of spermatids failed to spermiate in control animals, and 11% and 14% of spermatids failed to spermiate after 1 week of FSH inhibition or testosterone suppression, respectively. After 1 week of combined FSH and testosterone withdrawal, 50% of the spermatids in the testis failed to be released. A time course of testosterone suppression showed that after 4-5 weeks over 90% of spermatids failed to spermiate. We conclude that spermiation is highly sensitive to hormone suppression, with T and FSH acting synergistically to support spermiation, and that spermiation inhibition is a potential target for contraception.

Animals↗
PubMed1999

Linkage between male infertility and trinucleotide repeat expansion in the androgen-receptor gene.

BACKGROUND: Androgens acting via the androgen receptor bring about stimulation and maintenance of spermatogenesis. If mutations in the androgen-receptor gene interfere with the receptor's function, this effect may partly account for impaired spermatogenesis. We aimed to find out whether expansion of a trinucleotide repeat in the androgen-receptor gene is associated with male infertility. METHODS: We analysed 67 coded semen and blood samples from a predominantly white group of male infertility patients and controls. Clinical analyses included cause of infertility, sperm count, and reproductive hormone concentrations. Analysis of trinucleotide (CAG) repeat length and point mutations in the androgen-receptor gene was done by PCR, single-stranded conformational polymorphism, and DNA sequencing. FINDINGS: Screening and characterisation of the androgen-receptor gene in 35 patients and 32 controls showed no point mutations in the gene. 30 of the infertile patients had idiopathic azoospermia or oligozoospermia, and these men had significantly longer CAG repeat tracts than controls (mean 23.2 [SE 0.7] vs 20.5 [0.3], p=0.0001). The odds of having CAG repeat lengths of 20 were six-fold higher for fertile men than for men with a spermatogenic disorder. INTERPRETATION: Our results indicate a relation between CAG repeat length in the androgen-receptor gene and the risk of defective spermatogenesis. With the use of intracytoplasmic sperm injection, this mutation could be inherited, possibly leading to an increase in male infertility in future generations. Should further elongation of the CAG repeat occur in these future generations, there is an added risk of increased severity of male infertility, and potentially an increased incidence of neurodegenerative disease.

Adult↗