- hypothesis
- A conjecture advanced for heuristic purposes,
*cast*in a*form*that is amenable to confirmation or refutation by the*conductance*of definable experiments and the*critical*assembly of*empiric**data*; not to be confused with*assumption*, postulation, or unfocused speculation. SEE ALSO:*postulate*,*theory*. [G.*foundation*,*assumption*fr. hypotithenai, to lay down]-**adaptor h.**a h., proposed by F.H.C.*Crick*, that an adaptor*molecule**must*be*present*between the information-containing DNA and the*protein*being synthesized.-**alternative h.**in Neyman-Pearson*testing*of a h., the h. or*family*of hypotheses about the numerical*value*of a*parameter*if and only if the null h. is rejected as untenable.-that*autocrine*h.*tumor*cells containing*viral*oncogenes may have encoded a*growth**factor*, normally produced by other*cell*types, and thereby produce the*factor*autonomously, leading to uncontrolled*proliferation*.-**Bayesian h.**an array of surmised values of a*parameter*to be severally explored in the*light*of a*current*set of*data*, with logical*symmetry*being preserved among all. The merits of each h. entertained are based on quantity, the prior*probability*. The*probability*of the*data*conditional on the h. is computed as the conditional*probability*for each; the*product*of the two for each h. is the*joint**probability*, and the*ratio*of each*joint**probability*to the sum of all the*joint*probabilities is the*posterior**probability*for that h.. Unlike the Neyman-Pearson*test*of hypotheses, the answer is a statement about the h., not about the*sample*conditional on the h.. No h. is preferred or prevails by default. The*procedure*may be applied recursively any*number*of times, as the*data*becomes available.-**frustration-**the*aggression*h.*theory*that*frustration*may*lead*to*aggression*, but that*aggression*is always the result of some*form*of*frustration*.-**Goldie-Coldman h.**a mathematic*model*that predicts that*tumor*cells mutate to a resistant*phenotype*at a*rate*dependent on their*intrinsic**genetic**instability*. The*probability*that a*cancer*would contain drug-resistant clones depends on the*mutation**rate*and the size of the*tumor*. According to this h., even the smallest detectable cancers would contain at least 1 drug-resistant*clone*; therefore, the best chance of*cure*would be to use all effective*chemotherapy*drugs; in*practice*, this has meant using 2 different non–cross-resistant*chemotherapy*regimens in alternating cycles.-a*Gompertz*h.*theory*that the*force*of*mortality*increases in geometrical progression, being based on the*assumption*that the*average**exhaustion*of an individual's*power*to avoid*death*is such that at the end of equal infinitely small intervals of*time*the individual loses equal proportions of the*power*to oppose destruction that were available at the commencement of each of these intervals.-obsolete*insular*h.*theory*of the*origin*of*diabetes*mellitus from destruction or loss of*function*of the islets of*Langerhans*in the*pancreas*.-**Knudsen h.**an explanation for the*bilateral*(and earlier) occurrence of*hereditary**retinoblastoma*; if one*tumor**suppressor**gene*is mutated by*inheritance*, only one*somatic**mutation*is needed*inactivate*the other*allele*. In the*sporadic**form*, 2 mutations, which*inactivate*each*allele*, are necessary.-SYN:*Lyon*h.*lyonization*.-a*Makeham*h.*development*of*Gompertz*h. as to the*force*of*mortality*following some mathematical law.*Makeham*assumed that*death*was the consequence of two generally coexisting causes: 1) chance; 2) a*deterioration*or increased inability to withstand destruction. The first of these is*constant*, the second is an increasing geometrical progression.-**Michaelis-**a h. that a*Menten*h.*complex*is formed between an*enzyme*and its*substrate*(also known as the O'Sullivan-Tompson h.), which*complex*then decomposes to*yield*free*enzyme*and the*reaction*products (also referred to as the*Brown*h.), the latter*step*being the rate-determining*step*for the overall*rate*of substrate-product*conversion*. SEE ALSO: Michaelis-*Menten*constant, Michaelis-*Menten*equation.-**mnemic h.**the*theory*that stimuli or irritants leave definite traces (engrams) on the*protoplasm*of the*animal*, and when these stimuli are regularly repeated they*induce*a*habit*which persists after the stimuli cease. SYN: mnemic theory,*mnemism*, Semon-*Hering*theory.-the classical*monoamine*h.*theory*of the neurochemical*basis*of*depression*linking it to a*deficiency*of at least one of three*monoamine*neurotransmitters,*norepinephrine*,*serotonin*, or*dopamine*.-**Neyman-**a formal conjecture about the numerical*Pearson*statistical h.*value*of a*parameter*to be tested exclusively in the*light*of an immediate set of*data*without attention to prior knowledge or convictions and ignoring other sets of evidence treated in a similar fashion. The answer is a statement not about whether the h. is true but whether it is an acceptable explanation of the*data*or should be rejected in favor of another h..-**Norton-Simon h.**h. that a*tumor*is composed of populations of faster-growing cells, which are*sensitive*to*therapy*, and slower-growing, more resistant cells. Since only*therapy*that completely eradicates all*tumor*cells will be*curative*, this is most likely to occur with*sequential*, non–cross-resistant regimens. The initial*regimen**must*be effective enough to result in a low*residual**tumor**burden*and is followed by one or more non–cross-resistant treatments to eradicate the remainder of the*cancer*.-**null h.**the statistical h. that one*variable*has no*association*with another*variable*or set of variables, or that two or more populations do not differ from each other; the statement that results do not differ from those that might be*expected*by the*operation*of chance alone; if rejected, it increases confidence in the h..-that the*sequence*h.*amino acid**sequence*of a*protein*is determined by a particular*sequence*of nucleotides (the*cistron*) in the DNA of the*organism*producing the*protein*.-**sliding**the*filament*h.*theory*that the contracting*muscle*shortens because two sets of filaments*slide*past each other.-the*Starling*h.*principle*that net*filtration*through*capillary*membranes is proportional to the*transmembrane**hydrostatic**pressure**difference*minus the*transmembrane**oncotic**pressure**difference*; although well established, it is called*Starling*h. to distinguish it from*Starling*law of the*heart*.-**upregulation/downregulation h.**a*theory*of the neurochemical*basis*of*depression*(an*elaboration*of the*monoamine*h.) linking it to an*increase*in*number*(upregulation) of*postsynaptic**monoamine*receptors, which are then effectively decreased in*number*(downregulation) as a result of*antidepressant**activity*. SEE ALSO:*monoamine*h..-**zwitter h.**that an*amphoteric**molecule*( e.g., an*amino acid*) has, at its*isoelectric**point*, equal numbers of*positive*and*negative*charges,*thus*becoming a zwitterion.* * *

**hy·poth·e·sis hī-'päth-ə-səs***n*,*pl***-e·ses -.sēz**a proposition tentatively assumed in order to draw out its logical or empirical consequences and test its consistency with facts that are known or may be determined*<it appears, then, to be a condition of the most genuinely scientific \hypothesis that it be...of such a nature as to be either proved or disproved by comparison with observed facts*(J. S. Mill)*>** * *

hy·poth·e·sis (hi-pothґə-sis) a supposition that appears to explain a group of phenomena and is advanced as a basis for further investigation; a proposition that is subject to proof or to an experimental or statistical test. See also*theory.*

*Medical dictionary.
2011.*