After a specific number of subcultivations in the laboratory, normal human cells undergo irreversible cessation of mitosis and enter a non-dividing state.
This phenomenon is known as:
B. The process of aging can be classified as primary aging, which accounts for the relatively constant lifespan observed in a species, and secondary aging, which explains much of the unpredictability among individual members of the species. The primary aging process is most probably constitutional and is probably wired in the cellular machinery. This was demonstrated by Hayflick and colleagues, who showed that the maximum number of cell divisions that can occur in normal human cells in culture is approximately 40–60. Many functional capacities of the cells reduce as the cells approach the Hayflick limit. This ‘Hayflick phenomenon’ is under genetic control; it is not limited to laboratory culture methods. Pruning is a developmental phenomenon by which unnecessary synapses formed during brain development are removed. Apoptosis refers to programmed cell death.
The Hachinski Ischaemic Score is used to aid clinical differentiation of Alzheimer’s dementia from vascular dementia.
Which of the following clinical features support a diagnosis of Alzheimer’s dementia rather than vascular dementia?
D. The Hachinski Ischaemic Score is an easy-to-use clinical tool that aids in the bedside differentiation of Alzheimer’s dementia from vascular dementia. It has been validated in patients with pathologically confirmed dementia. A cut-off score ≤4 supports a diagnosis of Alzheimer’s dementia while a score ≥7 favours vascular dementia. These cut-off values have a sensitivity of 89% and a specificity of 89%. Abrupt onset, fluctuating course, history of stroke, presence of focal neurological symptoms and signs strongly favour a diagnosis of vascular dementia. Other supporting features for a diagnosis of vascular dementia include stepwise deterioration, presence of nocturnal confusion, absence of changes in personality, presence of emotional incontinence, depression and a history of hypertension.
Which of the following statement regarding the assessment of activities of daily living (ADL) in elderly people is correct?
A. In dementia complex ADL that require use of tools and equipment (instrumental ADLs) are affected earlier than basic ADL. Although self-report ADL measures are rare, they do exist. For example, the ADL-Prevention Instrument (ADL-PI) has a self-rated version and an informant version. Self-ratings are found to be closer to research observer’s ratings, while family members tend to under-rate the ADL. Data from self-report of functioning predicts mortality better than informant data. The Barthel Index consists of 10 items that measure a person’s ADL and mobility. It can be used to determine a baseline level of functioning and also to monitor changes in ADL over time. It is rated by carers or professionals. Currently, functional capacity measures are being used increasingly in pharmacological trials of patients with dementias as primary outcome measures. ADL scales are not gender biased and are commonly used in both sexes.
Schizophrenia-like psychosis is a prominent feature of which of the following dementing illnesses?
D. Huntington’s disease is inherited in an autosomal dominant fashion. It is a neurodegenerative disorder related to expansion of a trinucleotide repeat sequence in the short arm of chromosome 4. Clinical features include a triad of choreic movements, cognitive decline, and psychiatric syndromes starting in the fourth to fi fth decade. Psychiatric presentation is usually variable and can precede motor and cognitive changes. Most common psychiatric problems include change in personality (impulsive, disinhibited, and dissocial) and depression. Paranoid schizophrenia-like symptoms occur in 6–25% of cases. Such schizophrenia-like presentation is very rare in other conditions listed.
A 78-year-old man is treated with diazepam by his general practitioner for disabling anxiety related to a recent bereavement.
The half-life of diazepam is most likely to be increased in this man due to:
D. Body composition changes with advancing age resulting in alterations in the way drugs are metabolized and circulated. Muscle mass and body water decline by as much as 25% by age 70 while the body lipid content increases. Body fat constitutes >40% of body weight in elderly women and >30% in elderly men. As a result, elderly people have a larger volume of distribution and longer half-life of lipophilic drugs. Lipid-soluble drugs such as diazepam have greater volume of distribution and half-life with slower clearance in elderly individuals.
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